Light- and ABA-triggered stomatal movements on epidermal strips peeled from wild-type and CPK13-overexpressing plants. Two CPK13-overexpressing lines (denoted OE13#3 and OE13#4) were compared with the Arabidopsis wild-type line (Columbia [WT]). After a 12-h-long period of darkness, light was switched on at time 0. Average stomatal aperture (35 or more stomata per epidermal strip) was measured at 0, 30, 60, and 180 min. At this time, stomatal closure was triggered by adding the plant stress hormone ABA (10 µm; black arrow) and average stomatal aperture (35 or more stomata per epidermal strip) was measured at 200, 240, and 300 min. Data are means ± se from 250 or more stomata from six independent plants by genotype. **P ≤ 0.01 and ***P ≤ 0.001 by Student’s t test.