The MSTO-211H cell line was established in 1985 from the pleural effusion of a patient with biphasic malignant mesothelioma of the lung, who had received prior combination chemotherapy with multiple drugs. MSTO-211H cells possess high-affinity EGF binding sites and express neuron-specific enolase (NSE) as well as the α and β subunits of human chorionic gonadotropin (HCG). No dopamine decarboxylase (DDC), bombesin, or neurotensin were detected. The MSTO-211H cells overexpress the c-myc proto-oncogene, but no gene rearrangement or amplification was observed. Expression of v-src, v-abl, v-erbB, c-raf1, Ha-ras, Ki-ras, and N-ras was positive in MSTO-211H cells; however, no expression of the oncogenes N-myc, L-myc, c-myb, c-fos, v-fes, v-fms, or v-sis was detected. The saturation density of MSTO-211H cells can reach up to 4×10⁵ cells/cm², but at this density, the cells begin to detach from the surface.