cAMP-dependent protein kinase (PKA) is similar to the substrate specificity of US3 PK, which can regulate apoptosis.140US3 can phosphorylate the regulatory subunit of PKA, such as the autophosphorylation site of RIIα, to promote a redundancy of anti-apoptotic events.140, 141 In addition, programmed cell death protein 4 (PDCD4), a tumour suppressor, interacts with HSV-1 US3 PK to regulate apoptosis.142. The gene discussed is PDCD4; the disease is neoplasm.