Figure 1.

Optimization of medium conditioning. BEAS-2B, 1799, 1198, and 1170-I cells were cultured for 24 h in fresh media as indicated. Cells and cell debris were removed by centrifugation from the collected media, and supernatants were used as conditioned media. LDH activities were measured in the conditioned media and normalized by cell number. All of the data represent the means ± standard deviations obtained from four independent experiments. EGF and P.E. indicate epidermal growth factor and pituitary extract, respectively.