Time necessary for Dig1 pre-incubation to achieve a significant preventive effect of subsequent R intoxication. The study is performed with R400 intoxication on HepG2, cell viability is measured as in Fig. (1). First D (2% - dotted line with squares) was applied (time on × axis) 15, 30 min, 1 to 24 h before R400 (96 ppm during 24 h - grey line with triangles), in comparison to M (black line with diamonds). More than 40% viability (R effect in these conditions) is obtained only after at least 6 h of D exposure (increasing dotted line).