Western blot was performed using Anti-p14ARF Polyclonal Antibody(Product # PA1-16662) and a 16kDa band corresponding to p14ARF/p16INK4a was observed in HeLa and DU 145, but not in OVCAR-3, U-2 OS and HEL 92.1.7. Nuclear enriched extracts (30 µg lysate) of HeLa (Lane 1), NIH:OVCAR-3 (Lane 2), DU 145 (Lane 3), U-2 OS (Lane 4), HEL 92.1.7 (Lane 5) were electrophoresed using NuPAGE™ 12% Bis-Tris Protein Gel (Product # NP0342BOX). 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) and detected by chemiluminescence with Goat anti-Rabbit IgG (Heavy Chain) Superclonal™ Recombinant Secondary Antibody, HRP (Product # A27036,1:4000) using the iBright FL 1000 (Product # A32752). Chemiluminescent detection was performed using SuperSignal™ West Dura Extended Duration Substrate (Product # 34076). Both p14ARF and p16INK4a are products of the same gene CDKN2A, and are isoforms produced by alternate splicing.