RAC1 and benign prostatic hyperplasia: In summary, our study employed both bioinformatic analyses on clinical BPH samples and laboratory modeling using human prostatic cell lines and BPH PDOs to identify and demonstrate (a) TIAM1 as a molecular driver of the branching phenotype in BPH and (b) inhibition of the TIAM1/RAC1 axis as a possible therapeutic approach to the effective treatment of BPH.