(5) In our study, Gdpd3-deficient CML stem cells showed decreased PGE2 levels, and in vitro treatment of Lgr4-hypomorphic mutant CML stem cells with PGE2 restored the interaction between active Foxo3a and β-catenin [14]. Here, LGR4 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.