We used siRNA sequences previously validated for both CDK11 gene transcripts, located 3′ to the CDK11p58 internal ribosomal entry site, and for both CK2α and CK2α′ catalytic subunit gene transcripts to test the effects of downregulation of CK2 alone, CDK11 alone, or combined CK2 and CDK11 in breast cancer cells [2,30]. The gene discussed is CDK11B; the disease is breast cancer.