siRNA-mediated depletion of Wee1 or treatment with the specific Wee1 inhibitor MK-1775 not only reduced cisplatin-induced H2AX phosphorylation in p53-negative Saos2 osteosarcoma cells, but also significantly potentiated Wip1-dependent sensitization to this chemotherapeutic drug. This evidence concerns the gene H2AX and osteosarcoma.