Figure 1. Proteins secreted by developing Dictyostelium cells.

(A) Experimental setup with wild-type cells on a porous membrane in contact with buffer. The developing cells aggregate and form fruiting bodies. During this period, molecules are secreted into the buffer. (B) Aliquots of the conditioned buffer were collected at the indicated times. Proteins in the conditioned buffer were separated by electrophoresis on a SDS-PAGE gel, which was then silver-stained.