CDK1 and cancer: We then determined the basis for the unexpected finding that CDK1 inhibited expression of pluripotency genes and cancer stem cell frequency, despite inhibiting KDM5B recruitment to NANOG. A possibility is that KDM5B recruitment and attenuation of H3K4me3 levels on SOX2 and NANOG may not be the critical determinants of KDM5B regulation of the expression of pluripotency genes.