Ab9645

Cells (1×10⁷) under 80% confluence or IVD tissues (0.1 g) were lysed in 1 mL ice-cold radioimmunoprecipitation assay (RIPA) buffer (Thermo Fisher; #89901) containing the protease inhibitor (Abcam; #ab142778). Equal amounts (30 µg) of proteins were loaded into the wells of SDS-PAGE gel and separated by electrophoresis. Proteins were transferred onto the PVDF (polyvinylidene fluoride) membrane (Sigma-Aldrich; #IPSN07852) and blocked with 5% fat-free milk for one hour at room temperature. The membranes were then incubated with primary antibodies, including anti-BMPR1a (Abcam; #ab264043), anti-BMPR1b (Abcam; #ab175385), anti-BMPR2 (Abcam; #ab96826), anti-Smad1/5/8 (Sigma-Aldrich; #SAB2702532), anti-pSmad1/5/8 (Sigma-Aldrich; #AB3848-I), anti-Smad4 (Sigma-Aldrich; #HPA019154), anti-Puma (Abcam; #ab9645), anti-Apaf-1 (Abcam; #ab233786), anti-CASP9 (Abcam; #ab184786), anti-CASP3 (Thermo Fisher; #MA1-16843), anti-HDAC1 (Abcam; #ab7028), and anti-β-actin (Sigma-Aldrich; #A2066). After incubation at 4 °C overnight, membranes were washed 5 times with a PBS buffer containing 0.1% Tween-20 (Sigma-Aldrich; #P9416) and then probed with secondary antibodies (Abcam; #ab6721 and #ab6728). Protein signals were recorded by the Bio-Rad Gel Imaging System (Bio-Rad, Shanghai, China; #1708265).

Tissue sections from formalin-fixed paraffin-embedded (FFPE) primary RS biopsies and CLL-RS matched sample biopsies were stained with an anti-PUMA rabbit polyclonal antibody (ab9645, Abcam, Cambridge, UK), followed by an anti-rabbit HRP-conjugated antibody and 3,3’-diaminobenzidine (EnVision™ System, Dako, Glostrup, DK) to visualize the reaction. Anti-PUMA specificity on tissues was tested on reactive lymph nodes and breast cancer samples. Immunohistochemical expression of PUMA was evaluated semiquantitatively as percentage of positive cells (0%; 0–25%; 25–50%; 50–75%: >75%) and as staining intensity (1+, 2+, 3+).