I-BRD9 is a selective cellular chemical probe of bromodomain-containing protein 9 (BRD9) with pIC50 value of 7.3 μM. I-BRD9 has high selectivity for bromodomain and extra terminal domain (BET) family and highly homologous bromodomain-containing protein 7 (BRD7). I-BRD9 can be used to identify genes regulated by BRD9 in Kasumi-1 cells involved in oncology and immune response pathways.