Fig. 7. Effect of protein phosphatase inhibition on K8 Ser73 and Ser431 phosphorylation. (A) HT29 cells, cultured under isosmotic conditions, were treated with tautomycin, cyclosporine-A or carrier control (DMSO) for 1 hour (37°C). Total cell lysates were then prepared and blotted with antibodies to total K8 or K8 Ser431-P. (B) HRT18 and HT29 cells were cultured in isosmotic or hyposmotic conditions for 5 hours, then DMSO (vehicle control; lanes 1, 4, 7, 10) or OA (100, 625 nM) were added to the culture media (1 hour). Total cell lysates were then prepared followed by immunoblotting.