TNF and Arthritis: In BPSM1 mice, bone marrow transplantation of wild-type or BPSM1 cells and genetic crosses with Tnfr1–/– mice suggest that while myeloid cells are necessary for TNF production in this model, TNFR1 signaling on non-hematopoietic cells, presumable synoviocytes, is required for the development of arthritis (Lacey et al., 2015).