Morphological and molecular features of BAC/AWBF. A: Mucinous adenocarcinoma with prominent BAC component harboring KRAS mutation and lacking EGFR mutation. Inset, DNA sequence chromatogram displaying codons 12 and 13 of KRAS in the same tumor. A heterozygous G>A transition at nucleotide 35 of the KRAS coding sequencing is observed. B: Nonmucinous adenocarcinoma with prominent BAC component lacking EGFR mutation. C: Nonmucinous BAC with EGFR mutation. Inset, sequence tracing after codon 746 (GGA) consistent with L747_T751delinsP mutation (deletion confirmed by sequencing reverse strand; data not shown). D: EGFR gene copy number analysis by FISH demonstrating high polysomy in a mucinous BAC with KRAS mutation (35G>T) and lacking EGFR mutation. Red signal indicates probe hybridization to the chromosome 7p (EGFR locus), and green signal represents hybridization of the chromosome 7q reference probe. Original magnifications: ×200 (A–C); ×1000 (D).