Effects of EGF on proliferation and tumor marker secretion of cervical cancer cells are reported together with the characteristics of EGF receptors on the cells. TA-4 producing cell line (OMC-1) originating from cervical squamous cell carcinoma and CA-125 producing cell line (OMC-4) originating from cervical adenocarcinoma, were used. Scatchard plot of EGF binding to OMC-1 indicated a single class of binding sites with a dissociation constant (Kd) of 360pM, whereas that of OMC-4 was curvilinear suggesting two classes of binding sites with a Kd of 170pM and 510pM. The theoretical maximum number of binding sites of OMC-1 and OMC-4 was 2.4 X 10(4) and 1.6 X 10(5), respectively. Effects of EGF on growth were studied by monitoring cell number and the incorporation of 3H-thymidine into the DNA of the cells. OMC-1 was stimulated by EGF at low concentrations (0.01-0.1nM) and inhibited at higher concentrations. OMC-4 was not stimulated by EGF. The TA-4 secretion of OMC-1 was slightly stimulated by EGF at low concentrations (0.01-1nM) and significantly stimulated at high concentration (10nM). The CA-125 secretion of OMC-4 was not stimulated by EGF. These results suggest that there are some differences between cervical squamous cell carcinoma and adenocarcinoma in the mechanisms of regulation of proliferation and tumor marker secretion by EGF.