RSPO1 and ovarian cancer: We found that all cell lines were WNT-responsive, as the addition of WNT and the co-ligand RSPO to the medium-activated AXIN2. In all five cell lines, SFRP2 had no significant inhibitory effect on WNT signalling, and in OVCAR3 cells (isolated from malignant ascites) SFRP2 significantly further activated AXIN2 compared to the activation provided by WNT plus RSPO (Fig. 5c and Supplementary Fig. 11g), suggesting a role of SFRP2 as a WNT activator in a subset of ovarian cancers.