Figure 2

Epithelial cell proliferation on different extracellular matrix proteins induced by epidermal growth factor plus insulin-like growth factor-I. Epithelial cells derived from nulliparous mice were plated as described in Fig. 1a. (a) At 24 hour post-plating, the media was changed to control (no growth factors), or a media containing EGF (50 ng/ml), IGF-I (300 ng/ml) or EGF+IGF-I (50 ng/ml + 300 ng/ml). ³H-thymidine incorporation into DNA was determined 24 hour later. ^* P < 0.01 that on poly-L-lysine, proliferation in EGF+IGF-I treated group is greater than in EGF- or IGF-I-treated groups. ^** P < 0.01 that on all ECM proteins, proliferation in EGF+IGF-I is greater than in EGF- or IGF-I-treated groups on ECM proteins and poly-L-lysine. (b) Epithelial cells were plated on indicated ECM proteins in medium without growth factors or hormones (control), with growth factors (GF: EGF 25 ng/ml + IGF-I 100 ng/ml), with or without estrogen (E2, 10 nM) and/or R5020 (23 nM). ^* P = 0.05 that values obtained with EGF + IGF-I + R5020 on LN and with EGF + IGF-I + E + R5020 on Col I and LN are significantly lower than EGF + IGF-I. (Adapted from [4] with permission from Endocrinology). Col, collagen; E2, estrogen; ECM, extracellular matrix; EGF, epidermal growth factor; FN, fibronectin; GF, growth factors; IGF-I, insulin-like growth factor-I; LN, laminin; PL, poly-L-lysine.