Loss-of-function mutations of the tumor-suppressor-like molecules Rnf43 and Znrf3 and elevated expression levels of the Wnt agonists Rspo2 and Rspo4 can also be counted among the prognostic biomarkers of breast cancer (Ciriello et al., 2015; Coussy et al., 2017; Katoh and Katoh, 2017). Here, RSPO2 is linked to neoplasm.