STAT5B and glioblastoma: Despite the potential heterogeneity of Src family kinase-mediated activation of STAT5 in GBM [31,32,33], we validated that inhibition with non-specific Src family kinase inhibitors, such as saracatinib and dasatinib, represents a broadly applicable means of inhibiting the EGFRvIII-Src-STAT5 axis and reliably inhibits phosphorylation of STAT5.