Formins and EB1s cooperate in regulating root development. A, Representative images f Arabidopsis wild-type Col-0 and Ateb1a Ateb1b Ateb1c triple mutant roots grown on vertically oriented agar media supplemented with DMSO or SMIFH2 (viewed through the agar). Scale bar, 1 cm. B–E, Measurements of root lengths (B), root apical meristem lengths (C), epidermal cell lengths (D), and deviation of root growth trajectories from the gravity vector, n > 21 (E). F, Impact of SMIFH2 on cell division patterns in wild type and Ateb1 triple mutant roots, visualized with FM4-64 staining and confocal microscopy. Scale bar, 20 µm. G, Frequencies of abnormal cell divisions in wild type and Ateb1 triple mutant roots after treatment with DMSO (mock) or SMIFH2. Roots were treated with 10 µM SMIFH2 in all experiments, n = 6. Whiskers denote minimal to maximal range of values. Statistically different average values are denoted by different letters as determined by one-way ANOVA test. P-values were calculated using unpaired t test.