GFER and nonpapillary renal cell carcinoma: To determine whether XMU-MP-1 inhibited ccRCC cell growth in 2D cultures through the Hpo pathway instead of an off-target effect, we generated Flag (Fg)-tagged wildtype (Fg-MST2WT) and a mutant form of MST2 carrying Y101D and D109A double mutations (Fg-MST2Y101D/D109A).