These results suggest that PTPN6 is silenced in more than 40–60% of the PTCL-NOS, ALK-neg ALCL, AITL, and 86% in ALK-pos ALCL subtypes, and may be an important regulatory mechanism of STAT3 activation in PTCL patients. This evidence concerns the gene PTPN6 and mature T-cell and NK-cell non-Hodgkin lymphoma.