MAPK1 and chronic kidney disease: In the lower dose of the KP-13-treated CKD group, ERK1 showed a trend to decrease (p = 0.085), the pERK1/ERK ratio remained significantly increased, the pERK1 level and the pERK2/ERK2 ratio tended to increase (p = 0.081 and p = 0.051 respectively), and pERK2 level was not different compared to the sham-operated group (Fig. 7B, D, E, F, and G, Figures S6 and S7).