Whole cell lysates were prepared in RIPA buffer (10 mM Tris, 150 mM NaCl, 1%Triton X-100, 0.5% NP-40, 0.5% deoxycholate, 0.1% SDS), proteins were separated on 4–12% Bis-Tris NuPAGE gels (Invitrogen), and transferred to PVDF membranes. Membranes were subsequently blocked with 5% milk in PBS-T (1X PBS, 0.1% Tween-20), and incubated with primary antibodies overnight. Affinity purified rabbit anti-mouse SerpinB2 antibodies were prepared after immunization with a purified recombinant GST-murine SerpinB2 fusion protein produced in E. coli as in [35]. Other antibodies used for western blot assays include: C/EBP-β (sc-150) (Santa Cruz Biotechnologies), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and α/β tubulin (Cell Signaling Technology, Inc.).