Distribution of EGF receptor/kinase substrates in cytoplasmic proteins of guinea pig various organs was studied. 35kDa and 38kDa proteins in SDS-PAGE were detected as substrates for the enzyme in lung, spleen, stomach, urinary bladder and skin. 35kDa protein is confermed as lipocortin-like 39K protein of neutrophils by the method of immunoblotting using antibody of 39K protein. The Ca^<2+>-dependent membrane binding activity protein was an important character for the protein phosphorylation by this enzyme. A recombinant 39K protein was also phosphorylated by EGF receptor/kinase and the amount of phosphorylated 38kDa detected on SDS-PAGE was increased by the time of incubation.