Figure 3.

The immunosuppressive effects of CsA and FK 506 originate from the binding of the drug-immunophilin complex to molecules of calcineurin (CN) and subsequent interaction with calmodulin (CAM). De-phosphorylation of activated T-cells class of transcription factors (NFAT) inhibits their translocation to the cell nucleus and subsequent activation of interleukin-2 (IL-2) expression. Activation of calcineurin leads to induction of nitric oxide synthase (NOS) by a dephosphorylation mechanism, overproduction of nitric oxide (NO) and cell death.