In the present study, SerpinB2 expression level was investigated in carcinosarcoma-derived Hs578T cell (MSL subtype), ductal carcinoma-derived HCC-38 cell (BL1 subtype) and invasive ductal carcinoma-derived MDA-MB-231 cell (MSL subtype). The gene discussed is SERPINB2; the disease is invasive ductal breast carcinoma.