AKT1S1 and Ewing sarcoma: Thus, one can speculate that the loss of critical wild-type EWSR1 activities in the regulation of gene expression, like the repression of PRAS40 and CFL-1 mRNAs that was shown to inhibit proliferation, migration and invasion of Ewing sarcoma family tumors, cannot be fully compensated by other FET members [55,56].