MDM2 and osteosarcoma: In order to analyze DNA damage caused by NPRL2 ectopic expression, we used three cell lines with different status of p53: 1) HEK293 cells expressing constitutively active p53; 2) H1299 non-small lung cancer cells, in which p53 is deleted40 and 3) U2OS osteosarcoma cells, where p53 is inhibited by MDM2.