a,b, Immunoblots of Fzd9b-V5 chimaeric proteins. Representative of two independent experiments. See also Supplementary Fig. 7. c, Quantification of the HEK293T cell STF assay with zebrafish Wnt9a, Fzd9b and Fzd4 chimaeras; n = 3 biological replicates each. d, Quantification of the HEK293T cell STF assay with human WNT9A, FZD9 and FZD4 chimaeras; n = 3 biological replicates each. e, Schematic of Fzd9b indicating the immunogen region used for antibody generation. f, Non-permeabilized immunofluorescence for Fzd9b chimaeras. Scale bar, 30 µm. Data are representative of ten fields of view from two independent experiments. g, Histograms of flow cytometry for Fzd9b chimaeras. Data are representative of two independent experiments using 10,000 cells for each condition. All STF assays were repeated independently with a similar trend. In c,d, the dots represent biological replicates from a single experiment, the bars represent the mean and the error bars represent the standard deviation; statistical analyses were by ANOVA compared to controls as indicated.