Characterization of summ4-1D mkk1/2. A, Morphological phenotypes of 3-week-old wild type (WT), mkk1/2, and summ4-1D mkk1/2. B and C, Expression levels of PR1 (B) and PR2 (C) in wild type, mkk1/2, and summ4-1D mkk1/2. Values were normalized relative to the expression of ACTIN1. Error bars represent standard deviations from three measurements. D, Growth of H.a. Noco2 on wild type, mkk1/2, and summ4-1D mkk1/2. Error bars represent standard deviations from three replicates. Statistical differences among the samples are labeled with different letters (P < 0.01, one-way ANOVA/Tukey’s test, n = 3).