PITX2 and malignant colon neoplasm: RGS16 is expressed in colon cancer cells, RGS2 is expressed in TC3 insulinoma cells, as well as RGS16 is expressed in T-lymphocytes, ventricular cardiomyocytes, and the liver.[1] Watson[49] considers RGS proteins are likely to have a variety of physiologic functions in mammalian cells.