CHEK2 and prostate cancer: PEITC arrests cells at the G2/M phase.74 In DU145 prostate cancer cells, this cell cycle arrest was mediated by an increase in p53, and a decrease in CDC25C protein levels.74d] PEITC activation of p53 in oral squamous cell carcinoma cell lines with a functional p53 caused an induction of the ataxia telangiectasia mutated serine/threonine kinase‐checkpoint kinase 2 (ATM‐CHK2) pathway as well as the expression of p21.