The jury is in: p73 is a tumor suppressor after all.

While p53 has been extensively characterized as a tumor suppressor, it has been more difficult to determine whether p63 and/or p73 play a similar role. Every system in which these family members have been studied, from cells to animal models to human tissues, seems to create more questions than answers. Tomasini and colleagues (2677-2691) demonstrate that one isoform of p73 is responsible for preventing tumor formation in vivo, providing critical validation of an isoform-based model of p73 function.