Effect of LEC-1–conditioned media on BaF3/MPLR proliferation. BaF3/MPLR and the parental BaF3 cells (1 × 10⁴ cells/well) were cultured in serum-free media in the presence of medium alone (control), or conditioned media from untreated A12 and C7 LEC-1 clones (A12, C7) or from γ-INF/TNF-α–treated A12 and C7 LEC-1 clones (aA12, aC7), or from untreated or γ-INF/TNF-α–treated MPC11 (MPC11 and tMPC11, respectively). BaF3/MPLR and BaF3 cells were cultured at 37°C in a humidified atmosphere flushed with 5% CO₂. After 16 hours, cell proliferation was assessed using a colorimetric method (see Materials and Methods). The absorbance was read at 490 nm. The results are expressed as the mean ± SE. Results are representative of three separate experiments. The increase in proliferation was statistically significant for A12 and C7 conditioned media with respect to the control (*, P ≤ .05), and for aA12 and aC7 conditioned media with respect to the untreated LEC-1 clones (A12 and C7) (**, P≤ .05).