PPIB and rheumatoid arthritis: In studies of Plcl2-deficient mice, it has been shown that Plcl2 acts as a negative regulator of B cell receptor signalling and humoral immune responses [50], and in humans is involved in metabolism [51] and implicated in autoimmune diseases such as psoriasis [52], rheumatoid arthritis [53], and systemic sclerosis [54].