Studies by flow cytometry showed that most of the isolated and disaggregated crypt cells obtained from normal control colon [mean 90·7 (s.e.m. ± 2·1)%], ulcerative colitis [92·4 (s.e.m. ± 3·0)%] and colonic Crohn's disease [90·0 (s.e.m. ± 2·1)%] tissue expressed the epithelial cell-specific marker Ber-EP4 (Fig. 3). The gene discussed is EPCAM; the disease is ulcerative colitis.