R-spondin 1 （RSPO1） is a secreted protein that belongs to the R-spondin family, which consists of four structurally related proteins （RSPO1-4） that act as ligands for the Wnt signaling pathway. RSPO1 plays a crucial role in regulating Wnt/β-catenin signaling by binding to the LGR4-6 receptors and enhancing the activity of Wnt ligands. This interaction leads to the stabilization of β-catenin and the activation of Wnt target genes involved in cell proliferation, differentiation, and stem cell maintenance. RSPO1 has been implicated in various developmental processes, including embryogenesis, tissue regeneration, and stem cell self-renewal. Dysregulation of RSPO1 signaling has been associated with several diseases, such as cancer and developmental disorders.