Activation of developmental genes in neoplastic transformation.

The view is advanced that it is important to fix the stage of development corresponding to the pattern of expression of oncodevelopmental proteins in neoplastic transformation and neoplasia. From a map of development focused on events beginning with the zygote and ending with the establishment of fetus and placenta, it is possible to explain why certain developmental gene products are restricted to fetus or placenta or distributed in both. It also suggests which products can be expected to be expressed concordantly in neoplastic transformation and in neoplasia.