Purity >98% by HPLC. PFI-3 is a potent and selective polybromo 1 (PB1) and SMARCA4 (SWI/SNF related, Matrix associated, Actin dependent Regulator of Chromatin, subfamily A, member 4) inhibitor (Kd values are 48 and 89 nM respectively). SMARCA4, also known as BRG1 (Brahma-Related Gene1), is part of the SWI/SNF (SWItch/Sucrose Non-Fermentable) family of proteins. Loss of function of SMARCA4 and components of SWI/SNF has been linked to cancer development suggesting a tumour suppressor function for BRG1. SMARCA4 has also been shown to interact with the breast cancer gene BRCA1 (BReast CAncer 1, early onset), as well as to regulate the expression of the tumorigenic protein CD44.