PTPRK and T-cell non-Hodgkin lymphoma: It has also been reported that the PTPRK (receptor type tyrosine-protein phosphatase K) gene located at chromosome 6q is mostly deleted in extranodal NK-cell lymphoma and T-cell lymphoma, which results in STAT3 dephosphorylation and subsequent activation of STAT3 in approx. 50% of NK/T-cell lymphoma (257).