STAMBP and breast cancer: As shown in Fig. 4A, there was a slight increase in fluorescence intensity of BC after getting displaced by α-MSH and its lower positively charged analogues K-MSH (+ 2) and KK-MSH (+ 3), whereas the two most cationic analogues, KKA-MSH and KKK-MSH, displayed a remarkable increase in fluorescence intensity of BC.