It is located at a chromosomal region (11q23) frequently deleted in human cancers.27 Its mutations and alterations have been found in colorectal and other cancers.28, 29 Cancer-associated mutants of PPP2R1B have been shown to be incompetent to bind the B and/or C subunits in vitro, resulting in PP2A inactivation.30, 31 PP2A regulates numerous signaling pathways. This evidence concerns the gene PTPA and cancer.