p66Shc gene has a pro-apoptotic role in human cell lines and it is activated by a p53-independent pathway

p66Shc protein has been proposed to be an indispensable factor for p53-dependent, mitochondria-mediated apoptosis in mice. Here, we show that p66Shc plays a pro-apoptotic role also in cell lines of human origin such as SaOs-2 and HeLa, where p53 is either absent or inactivated, thus, suggesting that p66Shc pro-apoptotic role is independent from the presence of a functional form of p53. The active form of p66Shc is phosphorylated in Serine 36. We confirm the importance of Serine 36 phosphorylation for p66Shc pro-apoptotic role, and our results suggest that the kinase involved in this process is activated independently from p53.