RSPO1 and cancer: Leucine‐rich repeat‐containing G protein–coupled receptors (LGRs) are a subgroup of the seven‐transmembrane G protein‐coupled superfamily that regulates various physiological processes associated with various diseases,4 and its member LGR4‐6 has high homology.5 Many studies have recently explored the biological functions of LGR4‐6 in various human cancer types.6, 7, 8, 9, 10, 11, 12 LGR4‐6 plays an important role in activating the Wnt/β‐catenin pathway by binding with R‐spondin (RSPO) ligands, which are closely related to tumor progression and invasion.10, 11, 12