EGFR and glioblastoma: EGFR signaling has been associated to Cx43 expression.25 As Cx43 was increased in the TMZ-resistant GBMs (Figure 1), we asked whether this was caused by EGFR activation as a large number of GBM patients showed increased/activated EGFR.26 GBMs were treated with 200 μM TMZ for 72 h or vehicle (untreated) and then analyzed for surface EGFR by flow cytometry.