PTPN6 and chronic myelogenous leukemia, BCR-ABL1 positive: For example, SHP1 mRNA and protein levels were found to be significantly reduced in patients with chronic myelogenous leukemia as a result of hypermethylation of the PTPN6 promoter, and an in vitro study revealed that the overexpression of SHP1 negatively regulated several signaling pathways, including JAK2/STAT5 signaling [83].