Evidence for single-cell origin of 3-methylcholanthrene-induced fibrosarcomas in mice with cellular mosaicism.

Fibrosarcomas produced by s.c. injection of 5 micrograms of 3-methylcholanthrene in Pgk-1a/Pgk-1b mice carrying X-chromosome inactivation mosaicism for the phosphoglycerate kinase (PGK-1) gene contained only one type of phosphoglycerate kinase in seven of eight cases (88%), as judged from its electrophoretic mobility, indicating the single-cell origin of the tumor.