Bimolecular fluorescence complementation

For the BiFC assays, cDNA encoding amino acid residues 2 to 158 of Venus was fused to the C terminus of LYN cDNA (LYN-V1) (29), and cDNA encoding amino acid residues 159 to 239 of Venus was fused to the C terminus of FGFR3 cDNA (FGFR3-V2). The ECM of RCS cells was degraded by 4-hour treatment with 0.3% bacterial collagenase 2 (Gibco) in no serum DMEM. Cells were transfected using FuGENE6 (1 μg of DNA per well of 24-well plate), fixed using 4% paraformaldehyde 24 hours later, and counterstained for transfection using GFP antibody (table S2), and the percentage of Venus complementation in transfected cells was calculated.