PRKACA (protein kinase cAMP-activated catalytic subunit alpha) is a gene that encodes the catalytic subunit alpha of protein kinase A (PKA), a critical enzyme in the cyclic adenosine monophosphate (cAMP) signaling pathway. Functioning as the primary effector of cAMP, this kinase regulates a vast array of cellular processes, including metabolism, gene expression, cell cycle progression, and synaptic plasticity. Under basal conditions, the catalytic subunit is held inactive by regulatory subunits; upon cAMP binding, it is released and phosphorylates a diverse range of substrate proteins on serine and threonine residues. Beyond its physiological roles, aberrant PRKACA activity, particularly gene fusions and copy number gains, is a well-established driver of specific human diseases, most notably fibrolamellar hepatocellular carcinoma (FLC), where a characteristic DNAJB1-PRKACA fusion acts as the oncogenic driver.