TP53 and osteosarcoma: Also, the same group investigated the role played by p53 in the mechanism of action developed by three different human osteosarcoma cell lines, as follows: (i) U2OS cells containing the wild-type p53; (ii) SAOS cells, a p53-deficient cell culture; and (iii) MG-63 cells expressing mutant p53 after exposure to inorganic phosphate.