a, Western blot depicting activation of MAPKs by 40 nM purified PrpL or 40 nM flg22 in 5-day old seedlings of wild-type Col-0 and individual rack1::T-DNA insertion mutants. The same molecular weight region of the Western blot is shown as in Fig. 1b. b, Induction of CYP71A12 by 20 nM purified PrpL or 20 nM flg22 in 5-day old seedlings of wild-type Col-0 and individual rack1::T-DNA insertion mutants. c, RT-qPCR analysis of rack1a, rack1b, and rack1c transcript levels in the 5-day old Col-0 or amiR-rack1-es1 and amiR-rack1-es2 seedlings. d, RT-qPCR analysis of rack1a, rack1b, and rack1c transcript levels in Arabidopsis protoplasts transfected with amiR-RACK1-4 or amiRNA control. e, Western blot depicting activation of MAPKs by 40 nM purified PrpL or 40 nM flg22 in Arabidopsis protoplasts transfected with amiR-RACK1-4 or amiRNA control. The same molecular weight region of the Western blot is shown as in Fig. 1b. The data represent the mean ± s.d., n = 3 biological replicates (b, c, d); *P < 0.05; **P < 0.01, Student’s t-test.