Figure 4.

Test of the RSPO1 antibody specificity by immuno-florescence studies and Western blotting. a) Schematic representation of goat RSPO1 cDNAs used in transfection experiments in COS7 cells. The longest comprise the first initiator codon (ATG₁). The smallest encodes a putative protein beginning at ATG₁₅. The black rectangles with arrows depicted the location of the primers used in order to clone both cDNAs. b) RSPO1 and Protein Disulphide Isomerase (PDI) immuno-detection in COS7 cells transfected with RSPO1-ATG₁ or RSPO1-ATG₁₅ expression vectors. Scale bars = 5 μm. c) Western blot detection of RSPO1 on total proteins extracted from the cytosolic or nuclear compartments and from the heparin-supplemented culture medium of COS7 cells transfected with RSPO1-ATG₁ compared with none transfected cells (NT).