Enhancement of osteopontin expression in HepG2 cells by epidermal growth factor via phosphatidylinositol 3-kinase signaling pathway

Figure 1 Dose-dependent effect of EGF on osteopontin expres-sion in HepG2 cells. 1×10⁵ cells were plated in 6-well plates. Next morning, cell cultures (near 80% confluent) were incu-bated in serum-free medium for 24 hours. The cells were stimu-lated dose-dependently by epidermal growth factor. Positive control denotes cells in normal growth medium containing 10% fetal calf serum. A. Osteopontin mRNA level was analyzed by RNase protection assay on total RNA using a 486 base-pair probe and controlling the loading with a probe for β-actin. B. Quantitation of osteopontin mRNA levels is shown in (A). RDU ratio reflects relative density units of osteopontin mRNA di-vided by β-actin mRNA. C. The results from RNase protection assay were confirmed by Western blot of osteopontin protein. Tubulin was served as loading control.