Figure 3.
EGFR amplification is detected in both intrachromosomal and extra-chromosomal locations in the PC9DR cells. A. Metaphase FISH analysis using PC9DR1 cells. A subset (18%) of cells contain an intrachromosomal focal amplification of EGFR (arrow). B. Metaphase FISH using PC9DR2 cells. The amplification of EGFR is exclusively located on double minutes. EGFR (CTD-2257H21; green); MET (RP-11-95I120; orange); CEP 7 (aqua). C. The PC9DR2 cells loose their resistance in the absence of PF00299804. PC9GR4, DR1 and DR2 cells were cultured in the absence of PF00299804 for 18 passages. The IC50 for PF00299804 was determined by MTS assay every 6 passages. D. Metaphase (left) and interphase (right) FISH analyses from PC9DR2 cells after 18 passages demonstrates loss of EGFR-containing double minutes.