Transcription coactivator that plays a role in the regulation of cell expansion in leaf and cotyledons tissues. Component of a network formed by miR396, the GRFs and their interacting factors (GIFs) acting in the regulation of meristem function, at least partially through the control of cell proliferation (PubMed:19392710). Appears to function synergistically with GRF1 as a transcriptional coactivator. Acts together with GRF5 for the development of appropriate leaf size and shape through the promotion and/or maintenance of cell proliferation activity in leaf primordia. Plays a role in adaxial/abaxial patterning and growth in leaf morphogenesis. GIFs are involved in the positive regulation of cell proliferation of lateral organs in a functionally redundant manner. Together with GATA18/HAN, mediates cotyledon identity by preventing ectopic root formation through the repression of PLT1 expression (PubMed:22669825). Interacts with GRF1, GRF2, GRF5 and GRF9. Strongly expressed in actively growing and developing tissues, such as roots, upper stems, and shoot tips and flower buds. Also expressed in mature flowers. Not expressed in the shoot apical meristem (SAM). Highly accumulated in the proximal part of leaf primordia, in the key proliferative zone at the junction region between the leaf blade and leaf petiole. Small and narrow lateral organs, such as leaves, cotyledons, and flowers. Significant defects in the number of cells in both the leaf blade and leaf petiole (PubMed:22669825, PubMed:19392710). Excessive postmitotic cell enlargement in leaves (compensation phenotype) (PubMed:19392710). Plant missing GIF1/AN3 and OLI2, OLI5 or OLI7 have a strong compensation phenotype (PubMed:19392710). The double mutant an3 han-30 exhibits severe defects in cotyledon development such as ectopic roots formation at the apical region of the embryo and seedlings, and associated with an abnormal expansion of PLT1 expression from the basal embryonic region to the apical region (PubMed:22669825). Belongs to the SS18 family.