Two kinases important for regulating actin polymerization have been implicated in the required rearrangement of F-actin during Cryptosporidium infection: proto-oncogene tyrosine-protein kinase Src (c-Src) and phosphatidylinositol 3-kinase (PI3K) (20, 48, –, 50). The gene discussed is SRC; the disease is cryptosporidiosis.