Provide a mechanistic link between auxin and plasma membrane H(+)-ATPases (PM H(+)-ATPases, e.g. AHA1 and AHA2), and triggers PM H(+)-ATPases activity by promoting phosphorylation of their C-terminal autoinhibitory domain as a result of PP2C-D subfamily of type 2C phosphatases inhibition, thus leading to the acidification of the apoplast and the facilitation of solutes and water uptake to drive cell expansion (PubMed:24858935). Triggers plant growth probably by promoting cell elongation (By similarity). Regulates branch angles and bending (By similarity). Probably involved in light intensity mediated root development (PubMed:31325959). Interacts with and inhibits PP2C-D subfamily of type 2C phosphatases such as PP2C67/PP2C-D1. Expressed in etiolated hypocotyls, petioles, leaves and flowers. Confined to the midveins of petioles and leaf blades (PubMed:29258424). In flowers, only expressed in the filaments and stigma papillae (PubMed:29258424). Induced by auxin in an ABP1-dependent manner (PubMed:21223392, PubMed:29258424, PubMed:27999086). Triggered by brassinosteroids, including brassinolide (BL) (PubMed:29258424, PubMed:30649552). Accumulates in reduced red/far-red light ration (R:FR) conditions mimicking shaded conditions (PubMed:29258424). Repressed by abscisic acid (PubMed:29258424). Induced by light (PubMed:31325959). Belongs to the ARG7 family.