Western blot was performed using Anti-PIK3CB Recombinant Rabbit Monoclonal Antibody (SC0580) (Product # MA5-32208) and a 110kDa band corresponding to Phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit beta isoform was observed across the cell lines tested and the expression was found to be low in MDA-MB-231 when compared to T-47D. Nuclear enriched extracts (30 µg lysate) of MCF7 (Lane 1), DU 145 (Lane 2), T-47D (Lane 3), MDA-MB-231 (Lane 4), NIH:OVCAR-3 (Lane 5), HEL 92.1.7 (Lane 6) were electrophoresed using NuPAGE™ 4-12% Bis-Tris Protein Gel (Product # NP0321BOX). Resolved proteins were then transferred onto a Nitrocellulose membrane (Product # IB23001) by iBlot® 2 Dry Blotting System (Product # IB21001). The blot was probed with the primary antibody (1:1000 dilution) and detected by chemiluminescence with Goat anti-Rabbit IgG (Heavy Chain) Superclonal™ Recombinant Secondary Antibody, HRP (Product # A27036,1:6000 dilution) using the iBright FL 1000 (Product # A32752). Chemiluminescent detection was performed using Novex® ECL Chemiluminescent Substrate Reagent Kit (Product # WP20005).