FIGURE 2 

An HGF pulse is able to stimulate a sustained migratory response. (A) Hypothetical input functions to the gene regulatory network. Blue: pulse; black: constant; green: oscillatory; yellow: nonlinear increase; red: exponential decay. (B) A short HGF input pulse is able to induce a sustained migratory response. HGF-induced migration distance of HaCaT cells for untreated (control), prolonged incubation (30 h), prolonged incubation (30 h) with actinomycin D inhibition (5 g/ml) and short time (1.5 h) incubation with 10 ng/ml recombinant human HGF is shown (from left to right). For short time treatment, cultures were washed extensively after stimulation and media were replaced. Error bars denote s.d. of the mean migration distance from three independent experiments. Note that migratory responses for a constant and pulsed stimulus are almost indistinguishable.