TBX21 and mature T-cell and NK-cell non-Hodgkin lymphoma: Gene expression profiling has identified two molecular subtypes of peripheral T‐cell lymphoma, not otherwise specified (PTCL NOS): PTCL‐TBX21 and PTCL‐GATA3, characterized by overexpression of the Th1‐ and Th2‐transcription factors TBX21 and GATA3, respectively, and corresponding target genes [26].