Seedling hypocotyl measurement and phenotypes of ethylene receptor mutants. (A) seedling hypocotyl length of air-grown seedlings in the presence and absence of the ethylene biosynthesis inhibitor AVG. (B) etiolated and (C) light-grown seedlings, and (D) rosettes of ethylene receptor mutants. Common receptor mutations are highlighted in the yellow box for each set of mutants. Error bars indicate standard deviation. Quintuple: the quintuple receptor mutant.