EGFR and central nervous system cancer: We examined whether EGFR feedback activation by BRAFV600E inhibition was evident in vitro, by treating three BRAFV600E glioma cell lines (BRAFV600E homozygous line AM38 and BRAFV600E heterozygous lines DBTRG-05MG and NMC-G1) with 5 μM PLX4720, 1 μM HKI-272 or a combination of both drugs.