CDKN2A and cancer: Seven different protein markers of senescence (i.e., pRb hypo-phosphorylation, lamin B1 loss, p53 phosphorylation status, accumulation of p53, p21, p16, and gamma-H2AX proteins) were detected by Jochems and colleagues in a panel of cell lines from four cancer types induced to undergo senescence by treatment with either etoposide or alisertib [18].