HSP90-IN-13 (compound 5k) is a potent broad-spectrum inhibitor of HSP90 with an IC50 of 25.07 nM, exhibiting multitargeted activity against EGFR, VEGFR-2, and Topoisomerase-2. It blocks the MCF-7 cell cycle in the G2/M phase and induces apoptosis through a mitochondria-mediated pathway.