Adipose-derived stem cells may also influence tumour growth and progression through exertion of immunomodulatory effects on T cells within the tumour microenvironment due to the secretion of cytokines such as prostaglandin E2, TGF-β1, indoleamine 2,3-dioxygenase, hepatocyte growth factor (HGF), and inducible nitric oxide synthase. This evidence concerns the gene IDO2 and neoplasm.