Despite the increased intra-tumor heterogeneity of human ADC samples over clonally bred mice, we discovered a novel tumor epithelial subpopulation (referred to as C10 in the text), which was specifically found in human mutant-KRAS ADCs and KP tumors and virtually undetectable in human WT-KRAS ADCs and in murine healthy lungs. The gene discussed is KRAS; the disease is neoplasm.