FAS and bipolar disorder: In this regard, increased expression of TNFSF receptors TNFR1/2 (TNFRSF1A/B), FAS (TNFRSF6), DR4 (TNFRSF10A), and TWEAKR (TNFRSF12A) (33, 34, 35, 36, 37, 38, 39, 40, 41) and downstream markers BCL2 (42,43), BAX (42, 43, 44), BID (42), CASP3 (43,44), CASP8 (45), and CASP9 (44) have been found in the serum, hippocampus, and PFC of people with schizophrenia and bipolar disorder.