Recently, Manara et al. clarified that the engagement of CD99 and antibody against CD99 (0662mAb) would elicit caveolin-1-dependent endocytosis with the downstream response between the IGF-1R and RAS/Rac1, thus initiating processes akin to methuosis in Ewing sarcoma cells [29]. This evidence concerns the gene CD99 and Ewing sarcoma.