CHEK1 and neoplasm: As shown in Fig. 1A, silencing of BRD7 significantly increased the protein levels of CHK1 but not of CHK2, and this effect was consistently observed in multiple tumor cell lines, including U2OS, H1792, H358, HCT116, SKBR3, and MCF7 (Fig. S1A), suggesting that BRD7 negatively regulates the expression of CHK1 protein.