Bidirectional interactions between HPA and immunity contribute to their role in inflammation and cancers: HPA activation results in secretion of CRH, ACTH and cortisol modulating the immune response while immunity-related substances, such as interleukin-1 (IL-1), IL-6 and tumor necrosis factor alpha (TNF-α) can backwards stimulate the HPA axis (42). The gene discussed is TNF; the disease is cancer.