Fig. 1. ceh-20 mutants have defects in programmed cell death. X indicates cells that die in wild-type animals; X indicates programmed cell deaths of cells that survive in wild type animals; an open circle indicates cells that survive in ceh-20 mutants but undergo programmed cell death in wild-type animals. (A) In the P12 cell lineage of wild-type animals, the P12.a division axis is anterior dorsal left (adl) and posterior ventral right (pvr). (B) The P12 lineages of ceh-20 mutants did not show this evidence of transformation to the P11 fate. mab-5 lineage is from Kenyon (Kenyon, 1986). Cells in which MAB-5 protein is detected are indicated in blue, with data taken from Salser et al. (Salser et al., 1993).