Figure 4.
Resistance to MTX of nonmultiplying transformed cells. On day 14 of a 2° assay of 105 SA′ cells, cultures were untreated or treated with 200 nM MTX for 3 days. They then were subcultured without MTX for a 3° assay with 105 cells (Upper) or 103 cells mixed with 105 standard passage A′ cells (Lower). There is no obvious difference in transformation between untreated and MTX-treated cultures when subcultured without MTX in the 3° assay with either 105 cells, or with 103 cells on a background of A′ cells.