While dinaciclib treatment caused tumor regression in the NCI-H23 xenograft model, the other three MCL1:BCL-xL high mRNA ratio xenograft models (COLO 320DM, A2780 and 22Rv1) showed only ∼40–50% tumor growth inhibition, despite apoptosis induction within the tumors. Here, MCL1 is linked to neoplasm.