Although there are a number of studies relating the activation of PI3K/AKT/mTOR pathway with the activation of HIF-1α [38,39], and melatonin regulates the PI3K/AKT/mTOR pathway in several models [5,24], our results show that these events are not connected in Ewing sarcoma cells. Here, HIF1A is linked to Ewing sarcoma.