RAC1 and benign prostatic hyperplasia: In this study, using clinical BPH samples and 2D/3D cell culture models, we have utilized a combination of bioinformatic-based analyses, genetic-modulation studies, and a proof-of-concept pharmacological approach to identify T-lymphoma invasion and metastasis-inducing protein-1 (TIAM1), an activator of small GTPase RAC1 signaling, as (a) a driver of branching phenotype in BPH and (b) a promising candidate pathway for molecular approaches for therapeutic targeting of BPH.