Additionally, HDAC4 and HDAC9 expression is inversely correlated with Forkhead Box A1 (FOXA1), an important transcription factor in maintaining urothelial differentiation [9], and peroxisome proliferator-activated receptor gamma (PPARG), a steroid hormone receptor known for its oncogenic role in the development of BC [33]. Here, HDAC4 is linked to breast cancer.