The production of Regan isoenzyme (heat-stable, L-phenylalanine-sensitive term-placental alkaline phosphatase), human chorionic gonadotropin beta-subunit, and pregnancy-specific beta 1-glycoprotein by newly characterized human uterine cervical cancer cell lines, SKG-IIIa and SKG-IIIb, is reported. These cell lines were derived from a moderately differentiated epidermoid cancer partially mixed with epidermoid clear-cell components. At the end of the first 4 months in culture 2 sublines with different morphologies were identified. In nude mice, SKG-IIIa produce clear-cell epidermoid cancer with much glycogen, while SKG-IIIb grew as a moderately differentiated epidermoid cancer rich in tonofilaments. The presence of Regan isoenzyme was established by biochemistry, enzyme cytochemistry, immunocytochemistry, and immunoelectrophoresis. However, the copresence of small amounts of early placental alkaline phosphatase was also demonstrated. The alkaline phosphatase specific activities of SKG-IIIa cells and SKG-IIIb cells were 3.7 and 1.4 nmol per mg protein per min, respectively. The existence was proven by radioimmunoassay of human chorionic gonadotropin beta-subunit (SKG-IIIa, 5.0 mlU/mg protein; SKG-IIIb, 4.4 mlU/mg protein), pregnancy-specific beta 1-glycoprotein (SKG-IIIa, 0.7 ng/mg protein) in the culture media as a tumor cell product. The described cell lines may serve as a more representative model system for studies of regulation of oncodevelopmental genes in gynecological tumors in general and in epidermoid cervical cancer in particular.