Cross-analysis of mice harboring xenografts from the same original tumor and treated with each of the different modalities revealed subgroups with preferential sensitivity to AZD6244 (12.5%), BEZ235 (35%), or AZD6244 + BEZ235 (42.5%); another subgroup (10%) showed equivalent response to any treatment....Thirty-two samples (67.6%) harbored a KRAS mutation: 22 (55%) in codon 12; 5 (12.5%) in codon 13; 1 (2.5%) in codon 61; and 4 (10%) in codon 146.