XRCC1 and osteosarcoma: High levels of spontaneous γH2AX foci were also detected in osteosarcoma U2OS cells depleted of FoxM1 by RNA interference, and correlated with decreased levels of X-ray repair cross-complementing protein 1 (XRCC1) and breast cancer–associated gene 2 (BRCA2), two genes involved in DNA repair (Tan et al., 2007).