Oncostatin-M (OSM), an IL-6 family cytokine, exhibits varied roles in different patho-physiological conditions. Differential expression of OSM in response to varying stimuli indicates importance of its regulation of expression. The present study illustrated transcriptional induction of osm on treatment with chemical inducer, phorbol-12-myristate-13-acetate (PMA). Following initial hours of PMA treatment, a nuclear protein C/EBP-beta binds specifically to the CCAAT consensus sequence at the proximal end of the OSM promoter. Genistein (a specific Tyr phosphorylation inhibitor) leads to the interaction of CHOP (C/EBP Homologous Protein) with C/EBP-beta, thus negatively regulating it. Knockdown of C/EBP-beta also leads to inhibition of PMA-mediated OSM induction.