Fig. 1

Establishment of oral cell line in vitro cultures. Growth and passage of the normal oral gingival cell line HGF-1 (lower left) and Hs27 (not pictured) took 10–12 days to achieve 70% confluence. Proliferation of the oral cancer SCC cell lines varied, with the slowest (SCC4) achieving 30–40% confluence within 48–72 h and the fastest (SCC25 and CAL27) achieving 90–95% confluence over the same time