IGF1R and Ewing sarcoma: In Ewing sarcoma (ES) and SS, some patients have been observed to respond to IGF1R inhibitors and pazopanib (a multi-targeted RTK inhibitor), respectively (Pappo et al., 2011; Olmos et al., 2010; Sleijfer et al., 2009; Casanova et al., 2017), indicating targetable dependencies on kinase signaling in these two sarcomas, although the precise mechanisms of those dependencies have remained elusive.