Experimental systems to retain EGFR amplification present in the original tumor have thus largely relied on immediate orthotopic implantation of freshly resected tissue from GBM with EGFR amplification into nude mice [49, 70, 71] and by subsequent serial passaging in vivo of these xenograft tumors [42, 72, 73]. The gene discussed is EGFR; the disease is glioblastoma.