Figure 2.

(A) Typical profile of unbound VEGF, the source of which is located at x = 1. (B) Various choices for the chemotactic sensitivity of an endothelial cell to VEGF bound to its surface receptors, as a function of the fraction of activated VEGFR2 per cell face. (C–F) Average migration times (in hours) for a single cell to travel across a 1 mm × 1 mm domain as a function of increasing the maximum free VEGF concentration at a lattice site, for various choices of the chemotactic sensitivity function. Cells are assumed to respond to activated VEGFR2 on their surfaces, with chemotactic sensitivity taken as: (C) as proposed in equation (8); (D) cells are assumed to respond to free VEGF with chemotactic sensitivity as defined in equation (8) with activated receptor concentration A replaced by free VEGF concentration C; (E) receptor-kinetic law, for which τ(A) = e^{χ0A/(KDp(K+A))}, χ₀ = 0.4416 (pg/mm³) mm²/h, K = 2 pg/mm³; and (F) constant, χ₀ = 0.0046 mm²/(pg/mm³)/h.