SB-699551 is a selective and brain penetrant 5-HT5A receptor antagonist with a pKi of 8.2 nM. SB-699551 shows high selectivity over most other 5-HT receptor subtypes, dopamine receptors, and alpha1B adrenoceptor. SB-699551 disrupts Galphai/o-coupled and PI3K/AKT/mTOR signaling pathways, alters CREB, ATF1, AKT, PRAS40, S6K, and FOXO1 phosphorylation in breast tumor cells. SB-699551 can be used for the research of anxiety, breast cancer, and Alzheimers disease[1][2][3][4][5].