STAT3 and glioblastoma: Moreover, consistent with the RNA expression, results of our immunohistochemical staining confirmed elevated STAT3, pSTAT3, STAT5A, and pSTAT5A protein expression levels in primary (n = 31) and recurrent (n = 14) GBM tissues compared to non-tumor tissues (STAT3/5A vs. non-tumor: ~5.3-fold, p < 0.001; pSTAT3/5A vs. non-tumor: ~9.0-fold, p < 0.001) (Figure 1C,D).