FIGURE 4 |.

Soluble factor secreted by 168FARN cells accelerates proliferation of the 4T07 cells. (A) 4T07 cells were grown for 3 days at which point their medium was either left unchanged, or replaced by either 168FARN-conditioned medium or fresh medium, as indicated. Cells were collected 24 h later and counted. Cell numbers at day 3 were arbitrarily set at 1 in order to include the data from three independent experiments. (B) The experiment was performed as in panel (A). but the medium conditioned by 168FARN cells was fractionated by membrane ultrafiltration with a 3 KDa molecular cutoff. After complementing the low and the high MW fractions, respectively, with 10% serum and DMEM, the media were used to grow the 4T07 cells, as in panel (A). The two fractions were also combined as a control. ns, not significant; **p < 0.01, ***p < 0.001, all compared to Day 4 point.