Effects of various inhibitors on the hypocotyl phototropic curvature induced by BL in the Arabidopsis wild type (WT) and phot1, phot2, and phot1phot2 mutants. Three-day-old etiolated seedlings of wild-type, phot1, phot2, and phot1phot2 Arabidopsis were grown on the same vertical plates and exposed to BL illumination at a fluence rate of 100 μmol m⁻² s⁻¹ for 12 h. A, Effects of 2 mm EGTA. B, Effects of 1 mm LaCl₃. C, Effects of 10 μm U-73122 (10 μm U-73343, an inactive analog, was used as the control). D, Effects of 20 μm  RR. The values are averages of three independent experiments (45–60 measurements each) with sd.