SHP-1 was initially classified as a tumor suppressor phosphatase [179] since its silencing, due to hypermethylation of CpG islands in the PTPN6 promoter region, is frequently associated with a poor prognosis and worse outcome in different types of cancers [180,181,182,183,184,185,186,187,188,189]. Here, PTPN6 is linked to cancer.