PTPA and neoplasm: It is intriguing that in MDA-MB-231 tumor cells most endogenous B56γ protein was found in the cytosolic fraction (Fig. 1i), and in complex with endogenous liprin-α1 (Fig. 1l), suggesting that liprin-α1 drives a large fraction of the B56γ/PP2A holoenzyme at PMAPs to regulate tumor cell migration.