Fig. 5. Effect of hyposmotic stress on K8 and K18 phosphorylation in human colonic cell lines and ex-vivo-cultured colonic biopsies. (A) Three human colonic cell lines (HT29, HRT18 and Caco2) were cultured in isosmotic (I) or hyposmotic (H) medium at 37°C for 6 hours. Total cell lysates were blotted with antibodies to the indicated antigens. (B) Total tissue lysates were generated from normal human colon biopsies immediately upon isolation (none), or after culturing in isosmotic (Iso) or hyposmotic (Hypo) conditions (37°C, 6 hours). Lysates were then blotted with antibodies to total K8 or to K8 Ser431-P.