JN122 is a spiroindoline-containing molecule that acts as an MDM2 inhibitor. It disrupts the MDM2/p53 protein-protein interaction, exhibiting potent antitumor effects in vivo. JN122 demonstrates antiproliferative activity, with IC50 values of 39.6 nM in HCT-116 cells and 4.28 μM in HEK-293 cells. It induces the activation of p53 and its target genes, halts cell cycle progression, and triggers apoptosis.