GST-pull down assay to identify the region of BRCA1 interacting with PP1. (A) Fragments used in GST pull down assays (BR 2 to 5) are diagrammed. (B) Gel depicting co-precipitation of GST-bound BR-4 with PP1. Following incubation of GST-BRCA1 proteins with equal amounts of cell lysate, a western blot was performed and probed with an antibody to the catalytic region of PP1. (C) Analysis of the effect of mutations of the KVTF PP1 interacting domain on the BRCA1- PP1 interaction. GST-bound-BR4 V-A and GST-bound-BR4 F-A binds PP1 with decreased intensity, compared to WT GST-bound-BR4.