CDKN1A and neoplasm: Compared with Eμ‐myc; Pot1b∆/∆ mice, both Eμ‐myc; Pot1b∆/∆; p21+/− and Eμ‐myc; Pot1b∆/∆; p21−/− mice displayed significantly reduced tumor‐free survival, although the tumor‐free survival between the two p21 cohorts was not significant (Fig. 4A).