A, total cell lysates from PELP1 clone 20 or the PELP1 pooled clone were incubated with GST-pRb fusion proteins containing the A/B and C pocket domains, the A/B pocket domain, or the C pocket domain. The ability of T7-PELP1 to interact with pRb fusion proteins was analyzed using a GST pull-down assay, followed by Western blotting with an anti-T7 monoclonal antibody. B, shown is a schematic representation of GST fusion proteins used in the GST pull-down assays.