Fig 1: Loss of ATM is associated with low BRCA and RAD51 expression and inhibition of phosphorylation of MRN complex proteins in DLD-1 hATM (−/−) KO cell line. Change in BRCA1, BRCA2, and RAD51 protein levels (by WB analysis) following vehicle and niraparib treatment (50 mg/kg PO, QD 28 days or longer) in tumors from DLD-1 hATM (−/−) KO cell line tumor model, n=6 mice/arm (A); %pRAD50(Ser638)/Rad50 and %pNBN(Ser343)/NBN expression in DLD-1 hATM (−/−) KO cell line by WB analysis, compared to levels in Dld-1 parental cell line (%pRad50(Rad50)/beta-actin), (n=1) (B), and (%pNBN(NBN)/beta-actin), (n=1) (C) (niraparib at 3 µM and etoposide at 40 µM).