The ARF tumor suppressor: keeping Myc on a leash.

The ARF tumor suppressor protein acts in a checkpoint that guards against unscheduled cellular proliferation in response to oncogenic signaling. Deregulated expression of c-Myc induces ARF expression and apoptosis through the ARF-Mdm2-p53 axis. Our recent study reveals a new direct role for ARF in controlling c-Myc's oncogenic activity that is independent of p53. ARF binds to and selectively impairs the transactivation ability of c-Myc while leaving its transrepression ability intact. Biologically, ARF prevents hyper-proliferation and transformation caused by c-Myc and enhances c-Myc-induced apoptosis independently of p53. These new findings may be especially relevant for therapeutic strategies targeting c-Myc-induced cancers.