PTPRH and gastric cancer: In contrast to PTKs, the importance of protein tyrosine phosphatases (PTPs) in the regulation of IECs has remained largely unknown, with the exception that stomach cancer–associated protein tyrosine phosphatase–1 (SAP-1, also known as PTPRH), a receptor-type PTP, is specifically expressed in IECs [8] and might play a role in control of the proliferation or migration of these cells [9].