MST3-IN-1 is a selective and orally active MST3 inhibitor with an IC50 of 122.4 nM. It exhibits antiproliferative activity in HepG2 cells, effectively induces apoptosis, and causes cell cycle arrest at the G2/M phase. In HepG2 xenograft mouse models, MST3-IN-1 significantly suppresses tumor growth, making it useful for liver cancer research.