We observed that SF-1 and P450scc are co-expressed in PA cells of MENX-affected animals, and both siRNA-mediated silencing of the Nr5a1 gene and treatment with the SF-1 inhibitor IsoQ resulted in the down-regulation of Cyp11a1 in rat primary tumor cells and in LβT2 gonadotroph cells. The gene discussed is SF1; the disease is neoplasm.