STAT3 and glioblastoma: Previous reports have indicated that sorafenib treatment stimulates SHP-1 and/or SHP-2 tyrosine phosphatase activity in breast cancer [32], glioblastoma [30], HCC [14] and pancreatic cancer [31] and that orthovanadate reduces the sorafenib-induced inhibition of signal transducer and activator of transcription 3 (STAT3)- mediated tyrosine phosphorylation and increased PTP and SHP-2 activity in glioma cells [30].