Early enhancement of plating efficiency of primary mouse embryo cells by the carcinogen methylnitrosourea.

Primary mouse embryo cells, when placed on a regular pattern of replating, initially exhibit a cyclical pattern of proliferation. When such cells recover from the primary injury caused by the carcinogen methylnitrosourea, they acquire a markedly enhanced plating efficiency. This change is independent of the density of plating at which the cells were treated and is probably a true, induced, heritable change rather than a selection of a preexisting cell population. The change may be independent of changes in contact inhibition and may be one of the steps in the development of cancer in tissue culture.