The ratio for extracted-ion signal intensity was 80:1 (mutant:wild-type) by LC-MS2 analysis (Fig 3D, red trace), indicating that the mutant enzyme results in approximately 10-fold more LC-MS2 signal on a per mole basis, presumably due to improved ionization efficiency for asparagine relative to aspartic acid.[16] Therefore, based on the ratio of mutant:wild-type LC-MS2 signals (Fig 2D, red trace), the colon tumor sample contains approximately 3-fold more mutant CSNK1A1 than wild-type. The gene discussed is CSNK1A1; the disease is colonic neoplasm.