KIF2C-IN-1 (compound 7S9) is a cell-penetrating, selective KIF2C inhibitor with fluorescent properties (Ex/Em = 410/510 nm). KIF2C-IN-1 exhibits notable cytotoxicity and weak inhibitory effects on KIF2A/B. KIF2C-IN-1 prohibits the dissociation of KIF2C from microtubules. KIF2C-IN-1 inhibiting KIF2C reverses cross-resistance to microtubule-targeting agents. KIF2C-IN-1 reduces tumorigenesis in chemoresistant triple-negative breast cancer (TNBC) model in mice with the combination of Paclitaxel.