Fig. S1. rapGAPB⁻ cell morphology is rescued when expressing RapGAPB under the control of the promotor used in expression studies. rapGAPB⁻ mutant alleles exhibit an aberrant plaque morphology compared with wild-type cells grown on a bacterial lawn (i-iii). The plaque morphology of insertion and deletion alleles was also indistinguishable (ii,iii). The abnormal morphology of the rapGAPB⁻ mutant was completely restored to the wild type when RapGAPB was expressed under the control of the rapGAPB promotor also used to drive lacZ expression (iv).

Fig. S2. Representative prespore and prestalk markers are expressed in the rapGAPB⁻ mutant. AX4 or rapGAPB⁻ cells were transformed with cell-specific reporter genes. Expression was examined at both slug and early culminant stages. No differences in the expression of ecmAO-lacZ, psA-lacZ or ecmB-lacZ were observed. In both developing AX4 and rapGAPB⁻ cells, ecmAO-lacZ expression was found mainly in the prestalk region at the slug stage and in the upper and lower cups of culminants. psA-lacZ expression was found in the prespore region of slugs and throughout the spore mass of culminants. ecmB-lacZ expression was found in the cone and scattered throughout the slug, and in the upper cup and stalk of culminants. Scale bar: 1 mm.

Fig. S3. rapGAPB⁻ mutant cells show normal ecmB-lacZ, psA-lacZ expression in chimeras. AX4 or rapGAPB⁻ cells were transformed with cell specific markers. 10% of cells expressing these markers were mixed in chimeras with 90% unlabeled cells and developed. The expression of the markers was observed at both the slug and early culminant stages of development. The expression of psA-lacZ and ecmB-lacZ in chimeras was normal. Scale bar: 1 mm.