PTPN6 and cancer: Although extensive studies on SHP-1 have revealed that the expression of SHP-1 was compromised in most, if not all, cancer cell lines and tumor tissues examined.13, 43, 44 For example, compound like acetyl-11-keto-B-boswellic acid was able to inhibit constitutive STAT3 activation in multiple human myeloma cell lines by upregulating the expression of SHP-1.43 However, in our study, the regulation of SHP-1 function by luteolin is not at protein expression level.