Figure 1.

MTX effect on growth rates of three sublines. Cells (10⁴) were seeded from standard passages of A′ and SA′ and from transformed cells recovered by growth at low density for 3 days from the 4° assay of SA′ (4°, SA′) in MCDB 402 with 10% CS. MTX (200 nM) was added to half the cultures of each group. The cells were trypsinized for counting at daily intervals. Untreated cultures, open symbols; MTX-treated cultures, closed symbols. A′ cells, □, ▪; SA′ cells, ○, •; 4° SA′ cells, ▵, ▴.