Fig. 6. NC4 wild-type cells secrete AprA and CfaD. (A) NC4 cells were grown on a bacterial lawn on an agar plate. The cells were washed off and a piece of the agar was mixed with SDS sample buffer, heated and, while still hot and molten, the material corresponding to 10 µl of the agar was loaded on gels. Western blots of the gels were stained with affinity-purified anti-AprA or anti-CfaD antibodies. A 0.5 ng recombinant CfaD standard (His-tagged rCfaD) was also loaded on the CfaD gel. Molecular mass markers in kDa are shown at left. (B) Size fractionation of medium conditioned by NC4 cells growing in shaking culture with bacteria, and western blotting of the fractions, was done as described for Fig. 4.