MTOR and osteosarcoma: The identification of the phosphatidylinositol 3-kinase/mammalian target of rapamycin (PI3K/mTOR) pathway as a central vulnerability for therapeutic exploitation and subsequent detection of responsiveness of osteosarcoma cell lines to PI3K/mTOR inhibition87,88 or the detection of BRCAness in a substantial subset of osteosarcomas89 with the subsequent demonstration of susceptibility of osteosarcoma cells with a BRCAness signature to poly(ADP-ribose) polymerase (PARP) inhibition90 may serve as current examples of preclinical endeavors which deserve clinical evaluation.