[5] In addition, PPID participates in many biological processes, including mitochondrial metabolism, apoptosis, redox, and inflammation, as well as in related diseases and conditions, such as ischemic reperfusion injury, AIDS, and cancer.

[7][8] In addition to PPIase and protein chaperone activities, cyclophilins also function in mitochondrial metabolism, apoptosis, immunological response, inflammation, and cell growth and proliferation.

[6][7][8] PPID in particular helps chaperone the assembly of heat shock protein Hsp90, as well as the nuclear localization of glucocorticoid, estrogen and progesterone receptors.

In response to elevated reactive oxygen species (ROS) and calcium ion levels, PPID interacts with Bax to promote mitochondrial pore formation, thus releasing pro-apoptotic factors such as cytochrome C and AIF.

[10] As a cyclophilin, PPID binds the immunosuppressive drug CsA to form a CsA-cyclophilin complex, which then targets calcineurin to inhibit the signaling pathway for T-cell activation.