CASP3 and HIV infectious disease: Elevated levels of apoptosis-related gene expression like caspase-3 are observed in epithelial cells while genes involved in epithelial differentiation pathways like casein kinase 2A1 and Wnt 5A are down-regulated during primary HIV infection (Sankaran et al., 2008), supporting that the maintenance and renewal mechanisms of gut epithelial cells are impaired following HIV infection.