RSPO1 and chronic myelogenous leukemia, BCR-ABL1 positive: Previous reports have demonstrated that Lgr4/Gpr48 functions as a receptor for R-spondins in the Wnt/β-catenin signalling pathway37–39, and that the Ctnnb1 gene encoding β-catenin is crucial for the disease-relapsing capacity of CML stem cells40.