CHEK1 and cancer: However, few reports have implicated CHK1 in apoptosis via CHK1‐mediated phosphorylation of p73 at Ser47, resulting in a strong increase in p73 transcription activity in response to DNA damage.37 As p73 is overexpressed in vulvar cancer,38 one might speculate that the low activation of CHK1 in nucleus impairs p73‐mediated apoptosis and thereby provides cancer cells with survival advantages.