Figure 2.EPP1 expression is downregulated by COP1 mutation. (A) A quantitative RT-PCR assay of EPP1 transcript levels in cop1-4 and wild-type seedlings grown in darkness for 5 d. (B) GUS staining of ProPKL:GUS transgenic seedlings grown in darkness for 5 d. The enlarged image of cop1 hypocotyl is shown up-right. Bar, 2 mm. (C) COP1 transcript level in 5-d-old light-grown wild type and epp1 mutant. In (B and C), relative expression was normalized to that of UBQ1 and data represent mean ± SD of three biological replicates.