Establishment and some mutational characteristics of 3T3-like near-diploid mouse cell line.

A stable and nonmalignant near-diploid cell line, designated m5S, has been established by serial in vitro transfers of embryonic skin cells of ICR mouse. The cells are stable in karyotype and growth, display high sensitivity to contact inhibition of cell division, are nontumorigenic in nude mice, and the transformation and mutation may be reproducibly tested. Unlike most of the mouse cell lines, the m5S underwent a unique karyotypic change during establishment and showed high stability in a diploid range, making amenable to the study of mutagenesis. The m5S is nearly unique; it represents the second near-diploid cell line sensitive to postconfluence inhibition of cell division derived from mouse embryo cells to be reported and characterized. These cells are being successfully used for qualitative and quantitative studies of oncogenic transformation as well as mutation to drug resistance by radiation and chemicals.