Involved in the regulation of root gravitropism (PubMed:27748769). Functions redundantly with LAZY2 and LAZY3 in the control of root gravitropism (PubMed:27748769). Involved in the development of the root system architecture by influencing lateral root angles and primary root length (PubMed:28029738, PubMed:32130643). Functions redundantly with LAZY1, LAZY2 and LAZY3 to control plant architecture by coupling gravity sensing to the formation of auxin gradients (PubMed:28821594). Involved in the establishement of auxin gradient in primary and lateral roots upon gravitropic stimulation (PubMed:32130643). Involved redundantly with LAZY1 and LAZY2 in the regulation of both shoot and root gravitropism (PubMed:28765510). Mediates gravity signaling in statocytes downstream of amyloplast displacement, leading to the generation of asymmetric auxin distribution in gravity-responding organs (PubMed:28765510). Regulates the direction of polar auxin transport in response to gravity through the control of asymmetric PIN3 expression in the root cap columella (PubMed:28765510). Regulation of auxin flow by the three proteins LAZY1, LAZY2 and LAZY4 in statocytes influences plant architecture by controlling the growth angle of lateral shoots and lateral roots (PubMed:28765510). Localizes in the nuclei of cortical and endodermal tissues near root tips in both primary and lateral roots. Specifically expressed in roots (PubMed:28029738). Expressed in root tips (PubMed:32130643). Expressed in the endodermis of inflorescence stems and hypocotyls (PubMed:28765510). Highly expressed in the lower hypocotyl and root stele of young seedlings (PubMed:28821594). No visible phenotype under normal growth conditions (PubMed:27748769). Roots of plants lacking LAZY2, LAZY3 and LAZY4 exhibit a negative gravitropic response, and grow upward in the opposite direrction of root gravitropism (PubMed:27748769). Increased branch angles of lateral roots and reduced length of primary root (PubMed:28029738, PubMed:32130643). Plants overexpressing LAZY4 exhibit steep lateral root angles, upward leaf curling, shortened siliques and narrow lateral branch angles. Belongs to the LAZY family.