PTGDS and mature T-cell and NK-cell non-Hodgkin lymphoma: Moreover, although transcription factor NRF2, the positive regulator of HMOX1 expression [54, 55], was down-regulated by PTGDS inhibition, the expression of HMOX1 protein was increased in PTCL cells, and the interaction between PTGDS protein and HMOX1 protein might have influence on the stability of HMOX1 protein in PTCL cells, which needs to be further explored.