Culture medium supplementation
| Group | Supplement |
| 1 | — |
| 2 | 10% FCS (Invitrogen, Paisley, UK) |
| 3 | α-amylase (93 IU/l, Sigma-Aldrich, Poole, UK) |
| 4 | rhEGF (1 μg/ml) |
| 5 | rhEGF (10 μg/ml) |
| 6 | Dextrin–rhEGF (1 μg/ml rhEGF equivalent in PBS) |
| 7 | Dextrin–rhEGF (1 μg/ml rhEGF equivalent in PBS) and α-amylase (93 IU/l) (pre-incubated for 24 h at 37°C) |
| 8 | Dextrin–rhEGF (10 μg/ml rhEGF equivalent in PBS) and α-amylase (93 IU/l) (pre-incubated for 24 h at 37°C) |
FCS, fetal calf serum; PBS, phosphate buffered saline; rhEGF, recombinant human epidermal growth factor.