Epigenetic regulators are new popular targets for cancer treatment. One of the promising epigenetic drug targets is Bromodomain-containing Protein 4 (BRD4) that binds to acetylated histone lysine residues and stimulates transcriptional elongation leading to expression of growth-promoting genes. 

5-hydroxytryptamine receptors (serotonin receptors , 5-HT receptors) are a group of G protein-coupled receptors (GPCRs) and ligand-gated ion channels found in the central and peripheral nervous systems [1, 2]. They mediate both excitatory and inhibitory neurotransmission. The serotonin receptors are activated by the neurotransmitter serotonin, which acts as their natural ligand.