The invention provides isolated nucleic acids molecules, designated CSAPK nucleic acid molecules, which encode novel protein kinases. The invention also provides antisense nucleic acid molecules, recombinant expression vectors containing CSAPK nucleic acid molecules, host cells into which the expression vectors have been introduced, and nonhuman transgenic animals in which a CSAPK gene has been introduced or disrupted. The invention still further provides isolated CSAPK proteins, fusion proteins, antigenic peptides and anti-CSAPK antibodies. Diagnostic, screening, and therapeutic methods utilizing compositions of the invention are also provided.