CDK9 coprecipitates with ICP22 [55] and a short, transiently expressed sequence of ICP22 amino acids 193-256 is enough to inhibit kinase activity [51], while pS2 is retained in viral infection with ICP22 mutants lacking amino acids 240–340, but not 213–240 [56], indicating that this entire region is not necessary for binding CDK9. This evidence concerns the gene CDK9 and viral infectious disease.