CHEK1 and osteosarcoma: (Additional file 1: Figure S2C, D) as we have recently shown that USP37 regulates tolerance of replication stress by enhancing CHK1 activity so in order to gain insight into genes that correlated with knock down or overexpression of USP37, we proceeded with exome sequencing analysis in osteosarcoma cells overexpressing USP37 or in cells in which USP37 was depleted.