A method of determining sensitivity to cancer treatment includes the step of determining the presence of overexpression of MYC in a biological sample from a patient suffering from cancer, wherein the presence of overexpression of MYC indicates a sensitivity to a treatment by a CDK9 inhibitor and wherein the cancer is selected from the group consisting of carcinoma, leukemia, and lymphoma.

Disclosed is a polypeptide that includes amino acids 183-222 of CRIF, wherein the polypeptide does not include the full length CRIF1 amino acid sequence. Also disclosed is a nucleic acid molecule encoding this polypeptide, vectors including this nucleic acid molecule, and host cells transformed with these vectors. In some embodiments, methods are disclosed for treating a subject with cancer, comprising administering to the subject a therapeutically effective amount of an inhibitor of CDK12/CRIF1 interaction, thereby treating the cancer in the subject. In specific non-limiting examples, these methods can utilize CRIF1 polypeptides, nucleic acids encoding these polypeptides, and vectors including these nucleic acids.

The present disclosure provides, in some aspects, variant RNA polymerases, the use of which increases transcription efficiency while reducing the number of double-stranded RNA contaminates and run-on transcripts produced during an in vitro transcription reaction.