Genetic studies of vulva development in the nematode C. elegans have identified many genes that regulate cell proliferation.
A paper by Saffer et al. (PLoS Genetics, 7(12), e1002418. doi:10.1371/journal.pgen.1002418) reports isolation of a novel mutation (allele) in the promoter of the EGF family member lin-3. This allele, n4441, when placed in the background of another mutation in any one of the class B synMuv genes, causes a multivulva (i.e., excessive cell proliferation) phenotype. This defect results from the derepression of lin-3 expression.