To investigate the potential translation of the MCL1:BCL-xL mRNA ratio as a predicative biomarker of dinaciclib-induced apoptosis to the in vivo setting, four MCL1:BCL-xL high ratio (NCI-H23, A2780, COLO-320DM, 22Rv1) and three low ratio (JIMT-1, MDA-MB-231, PC-3) xenograft tumor models were selected (see Figure S1) for dinaciclib pharmacodynamic evaluation. The gene discussed is MCL1; the disease is neoplasm.