Fig. 2. AprA is secreted by starving Dictyostelium cells, but is not part of the CF complex. Conditioned starvation medium from wild-type cells was fractionated by sieving gel filtration chromatography. Western blots of the fractions were stained with affinity-purified rabbit antibodies against CF50, countin and AprA. On the SDS-polyacrylamide gels, the upper band stained with anti-countin antibodies is at 40 kDa, the CF50 band is at 50 kDa and the heavy AprA band is at 60 kDa. The affinity-purified anti-AprA antibodies stained a band at 56 kDa in fractions 28-30. Besides this band and the heavy band at 60 kDa, the anti-AprA antibodies did not stain any other band. See Fig. 3 for validation that the anti-AprA antibodies are staining the product of the aprA gene.