p73: Friend or foe in tumorigenesis

As p53 and its homologue p73 have significant sequence and functional similarities, p73 might also be expected to act as a tumour suppressor However, p73 is activated after DNA damage in a way that is distinct from that of p53. The existence of DeltaNp73 - an isoform of p73 that is encoded by a distinct promoter and that lacks the transactivation domain - further complicates matters. It seems to function as an oncogene by inhibiting both p73- and p53-induced apoptosis. So how can these opposing functions be reconciled in human tumours?.