TGF-β: An Important Mediator of Allergic Disease and a Molecule with Dual Activity in Cancer Development

Figure 3

The role of TGF-β in cell cycle regulation. Physiologically, TGF-β is a potent cell cycle inhibitor, inducing the expression of p15^INK4B and suppressing c-Myc expression. p15^INK4B prevents the formation of cyclin D-CDK4/6 complexes and displaces p21^Cip1 and p27^KIP1 from the cyclin D-CDK4/6 complex. The inhibitors CIP/KIP can then inactivate other G1 to S phase complexes and inhibit the cell cycle. Low c-Myc levels allow TGF-β to induce the transcription of p15^INK4B and p21^Cip21.