Induced myeloid leukemia cell differentiation protein Mcl-1(MCL1) plays an important role in inhibiting apoptosis and is expressed only during particular stages of cell differentiation and in response to specific signals. It is a viability-promoting protein that interacts with fortilin (an anti-apoptotic protein) and regulates cell viability. Specific differentiation- and apoptosis-inducing stimuli enhance the expression of this protein. MCL1 acts as a chaperone of fortilin by binding and stabilizing it. It also interacts and negatively regulates the proliferating cell nuclear antigen (PCNA), which a cell cycle-regulatory protein essential for G1 to S phase transition. Hence, it functions to retard the cell cycle progression.
