Functional expression of VvPIP2;4N in X. laevis oocytes. Pf of oocytes injected with VvPIP2;4N complementary RNA solution, or with water (control), was measured from swelling kinetics. The assay was performed with a 10-min preincubation in the absence or presence of 0.3 mm HgCl2. Values shown are means ± se (VvPIP2;4N, n = 12; VvPIP2;4N + HgCl2, n = 5; control, n = 20; control + HgCl2, n = 5). Histograms labeled by different letters differ significantly at P < 0.05 according to variance analysis and Tukey’s test.