To discover genes in the Ras pathway, we transposon mutagenized human CRC cells having had their active KRAS or BRAF oncogene removed by genome editing and used a two-step selection procedure where: (1) tolerance to low glucose was selected by culturing three weeks in medium with 0.4 mM L-glucose; and (2) the resulting clones were selected for having productive transposon integrations by culture in hygromycin-containing medium (Additional file 1: Figure S1). The gene discussed is KRAS; the disease is colorectal carcinoma.