Pattern of expression of c-erbB-2 oncoprotein in human fetuses.

The pattern of expression of the c-erbB-2 oncoprotein was investigated in whole mount preparations of 11 human fetuses by immunocytochemistry using two polyclonal antibodies, 20N and 21N. c-erbB-2 was widely expressed within all three germ layers. Expression remained relatively constant in epithelial, mesodermal and extraembryonic tissues, but varied over time during the development of the fetal skeleton. Western blotting failed to detect c-erbB-2 in normal fetal tissues but did confirm expression in a microvillous membrane preparation of placenta. c-erbB-2 expression is widespread in the human fetus and occurs at an earlier stage than epidermal growth factor receptor.