Silencing of endogenous COP1 in human bone osteosarcoma epithelial cells (U2OS), a primary osteosarcoma cell line with wild-type p53 and H1299, a p53-null human non-small cell lung carcinoma, revealed the absence of COP1 arrest cell cycle in a p53-dependent manner [92]. The gene discussed is TP53; the disease is osteosarcoma.