SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* Kanner Steven (Last) (First) (Middle) 2929 7TH STREET, SUITE 105 (Street) BERKELEY CA 94710 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Caribou Biosciences, Inc. [ CRBU ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) Chief Scientific Officer
	3. Date of Earliest Transaction (Month/Day/Year) 10/12/2021
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	10/12/2021		P(1)		99,548	A	$1.81	199,719	D
Common Stock	10/12/2021		P(1)		698	A	$1.81	200,417	D
Common Stock	10/12/2021		P(1)		14,614	A	$2.69(2)	215,031	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Option to purchase Common Stock	$1.81	10/12/2021		X			99,548	(3)	07/11/2027	Common Stock	99,548	$0.00	71,840	D
Option to purchase Common Stock	$1.81	10/12/2021		X			698	(3)	03/07/2028	Common Stock	698	$0.00	4,879	D
Option to purchase Common Stock	$2.69(2)	10/12/2021		X			14,614	(4)	09/30/2029	Common Stock	14,614	$0.00	132,134	D

Explanation of Responses:

1. These shares were acquired pursuant to the exercise of a stock option, as reported in Table II below.

2. The exercise price for this stock option was incorrectly reported as $2.68 per share on the reporting person's Form 3 filed on July 22, 2021.

3. This option became fully exercisable on June 30, 2021.

4. 1/4th of the shares subject to this option vested on October 1, 2020 and an additional 1/48th of the aggregate number of shares subject to the option have vested or will vest on the corresponding day of each month thereafter, subject to the reporting person's continued services to the Issuer through the applicable vesting dates.

Remarks:

	/s/ Barbara G. McClung, as attorney-in-fact	10/13/2021
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.