EXHIBIT 3

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS, that the undersigned hereby constitutes and appoints Zachary Bambach, Nicole Hatcher and Stephanie Brecher, and each of them, with full power to act without the others, his or her true and lawful attorney-in-fact, with full power of substitution, to sign any and all instruments, certificates and documents that may be necessary, desirable or appropriate to be executed on behalf of himself as an individual or in his or her capacity as a direct or indirect general partner, director, officer or manager of any partnership, corporation or limited liability company, pursuant to section 13 or 16 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and any and all regulations promulgated thereunder, including, without limitation, Forms 3, 4 and 5 and Schedules 13D and 13G (and any amendments thereto), and to file the same, with all exhibits thereto, and any other documents in connection therewith, with the Securities and Exchange Commission (the “SEC”), including, but not limited to, signing a Form ID for and on behalf of the undersigned and filing such Form ID with the SEC, and with any other entity when and if such is mandated by the Exchange Act or by the Financial Industry Regulatory Authority, granting unto said attorney-in-fact full power and authority to do and perform each and every act and thing necessary, desirable or appropriate, fully to all intents and purposes as he or she might or could do in person, thereby ratifying and confirming all that said attorney-in-fact, or his or her substitutes, may lawfully do or cause to be done by virtue hereof. This power of attorney is perpetual, unless revoked by the undersigned in a signed writing delivered to each of the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, this Power of Attorney has been signed as of the 29th day of February, 2024.

/s/ Peter J. Barris
Peter J. Barris

/s/ Forest Baskett
Forest Baskett

/s/ Ali Behbahani
Ali Behbahani

/s/ Ronald D. Bernal
Ronald D. Bernal

/s/ Ann Bordetsky
Ann Bordetsky

/s/ Carmen Chang
Carmen Chang

/s/ Philip Chopin
Philip Chopin

/s/ Anthony A. Florence, Jr.
Anthony A. Florence, Jr.

/s/ Jonathan Golden
Jonathan Golden

/s/ Scott Gottlieb
Scott Gottlieb

/s/ Mark Hawkins
Mark Hawkins

/s/ Jeffrey R. Immelt
Jeffrey R. Immelt

/s/ Aaron Jacobson
Aaron Jacobson

/s/ Patrick J. Kerins
Patrick J. Kerins

/s/ Hilarie Koplow-McAdams
Hilarie Koplow-McAdams

/s/ Vanessa Larco
Vanessa Larco

/s/ Julio C. Lopez
Julio C. Lopez

/s/ Tiffany Le
Tiffany Le

/s/ Mohamad H. Makhzoumi
Mohamad H. Makhzoumi

/s/ Edward T. Mathers
Edward T. Mathers

/s/ Gregory Papadopoulos
Gregory Papadopoulos

/s/ Kavita Patel
Kavita Patel

/s/ Scott D. Sandell
Scott D. Sandell

/s/ A. Brooke Seawell
A. Brooke Seawell

/s/ Peter Sonsini
Peter Sonsini

/s/ Melissa Taunton
Melissa Taunton

/s/ Paul E. Walker
Paul E. Walker

/s/ Rick Yang
Rick Yang

Arcellx, Inc. SCHEDULE 13D/A