To determine the mechanism underlying the increase in intestinal polyp number in the absence of ERBB3 on a C57BL/6J background, transcript data from colon polyps lacking ERBB3 was compared to polyps from littermates with wild-type levels of ERBB3 revealing 509 genes characteristic of ERBB3-deficient colon polyps (Fig 2A). The gene discussed is ERBB3; the disease is polyp.