Rapamycin is able to complete its functions by its ability to prevent cytokine signaling that promotes lymphocyte growth and differentiation.

To do so, upon entering the cytoplasm, rapamycin binds to the FK binding protein, which monitors the activity of the mechanistic target of rapamycin (mTOR). Once activated, the mTOR inhibits interleukin (IL)-2-mediated signal transduction, which stops the cell cycle during the transition between the G1 and S phase. As a result, further bacterial cell-cycle progression and proliferation is prevented.