[2 malignant cell lines derived from strain L6 of rat myogenic cells]

A nonfusing variant M4 of the L6 line of rat myoblasts was isolated. This subline was tumorigenic when inoculated into suckling rats. Comparative studies of cells growth in vitro, serum requirement, cell adhesiveness and capacity to form colonies in soft agar confirmed that M4 cells had undergone neoplastic transformation while L6 cells exhibited normal characteristics. Another subline designated as RMS4 was derivated from M4 cells tumors. Growth characteristics in vitro and karyotype analysis indicated that RMS4 cells presented a higher degree of transformation as compared with M4 cells. Both M4 and RMS4 cell cultures seem to produce a C-type virus.