To assess the clinical relevance of the PPP2R2A-Chk1 signaling axis, we next performed IHC staining to examine PPP2R2A and pChk1-S317 in serial sections of human primary breast cancer specimens (n = 137) (Supplementary Figs. S7A and S8A). The gene discussed is PPP2R2A; the disease is breast carcinoma.