The indolylkojyl derivative 18 (Figure 3, IKM5) was prepared by a simple three-component reaction and identified as a potent Grp78 inhibitor (Ki = 1.4 μM), which showed high antiproliferative activities against a panel of breast cancer cell lines (IC50 = 0.15 μM for MCF-7, 0.21 μM for MDA-MB-231, 0.54 μM for MDA-MB-468, and 3.5 μM for BT474 cells) [80]. Here, HSPA5 is linked to breast cancer.