Fig. 4.

Effect of treatment of postconfluent wild type Madin-Darby canine kidney (Wild Type MDCK) cell populations, occludin knockdown MDCK (Occ KD) cell populations, and zonula occludens-1 knockdown MDCK (ZO-1 KD) cell populations with 0 μM H₂O₂ or 55 μM H₂O₂ on ERK 1/2 phosphorylation/activation. Cell populations were treated with or without H₂O₂ for 10 min and then harvested for preparation of cell lysates. Solubilized proteins were separated by PAGE, transferred to nitrocellulose, and blotted for either ERK 1/2 protein (ERK, bottom) or ERK 1/2 [pT¹⁸⁵pY¹⁸⁷] (pERK, top). This is a representative experiment of at least three separate experiments using at least 2 independent lysate samples.