RETRA (hydrobromide) is a mutant p53-dependent activator of p73 that can inhibit cancer cells carrying mutant p53. RETRA (hydrobromide) increases the expression level of p73 , induces transcriptional activation of several common to transcriptional targets p53 and p73 , which leads to mutant p53- and p73 -dependent inhibition of tumor growth, reduction of colony formation and induction of effector caspases.