Tyrosine-protein phosphatase non-receptor type 11 (SHP-2 (PTP-2C)) Acts downstream of various receptor and cytoplasmic protein tyrosine kinases to participate in the signal transduction from the cell surface to the nucleus. Defects in PTPN11 are the cause of LEOPARD syndrome type 1 (LEOPARD1). This is an autosomal dominant disorder allelic with Noonan syndrome. The acronym LEOPARD stands for lentigines, electrocardiographic conduction abnormalities, ocular hypertelorism,Porcineulmonic stenosis, abnormalities of genitalia, retardation of growth, and deafness.