Inhibitory effect of ERS1 on the repression of the ethylene response is not blocked by ethylene. (A), (B) ethylene dose-response curve for two sets of ERS1-lacking mutants. (C) under a high ethylene concentration, ERS1 still exerts an inhibitory effect on seedling hypocotyl elongation. (D) ERS1 accumulation is elevated upon ethylene treatment; a and b represent ERS1 level from two independent wild-type plants. Error bar indicates standard deviation. ERS1: the ERS1 protein. NA: no ethylene treatment. Stained blot: membrane was stained with Coomassie Blue after the immunoassay to indicate relative protein amount. L1, L2, and L3 represent three independently identified isogenic mutants. A molecular weight marker is indicated at the position of 72 kD. Common mutations are highlighted in a box. P: probability of a numerically larger t in Student's t test or LSD-t test.