Analysis of the patterns of cell lineage observed during development of the nematode Caenorhabditis elegans, combined with selected cell ablation experiments, has revealed that while many cell fates are autonomously (intrinsically) determined, cell-cell interactions are required for a number of developmental decisions. Earlier genetic analysis of one key gene,
lin-12, had shown that this gene controls a number of bi-potential fate decisions involving such cellular interactions. Molecular analysis of this gene is now providing clues to its mode of action in mediating these cell-fate decisions.