The use of cloned gene probes to study differentiation in teratocarcinomas.

The molecular control of early embryonic gene expression can be studied in teratocarcinoma derived cell lines. Several genes known to be regulated during in vitro differentiation have been cloned and used to measure mRNA levels. In all cases studied there is good agreement between protein levels and mRNA levels, strongly implying transcriptional regulation. Two non-exclusive hypotheses have been proposed to explain transcriptional control: methylation of DNA and the interactive effects of cis-acting enhancer sequences and trans-acting proteins. Experiments with oncoviruses suggest both mechanisms may play a role.