CHEK2 and acute lymphoblastic leukemia: In support of the hypothesis that human T-ALL cells cultured in ACM may not effectively activate cell cycle checkpoints when experiencing DNA damage, CHEK1 and CHEK2 gene expressions were lower in human T-ALL cells when cultured in ACM relative to RPMI (and in some cases, SCM), with responses being more apparent in the more differentiated human T-ALL cells (Jurkat and Peer; Figures 2C–E).