Table 1.

Model parameter values

Parameter		Value	Remark
Actin monomer radius	δ	2.7 nm	(16)
Persistence length of actin	lp	15 μm	(49)
Attachment rate	ka	2.16 s−1	Assumed∗ 10 s−1 in Shaevitz and Fletcher (50)
Detachment constant	$k_{\mathrm{d}}^0$	2 s−1	Assumed∗ 0.5 s−1 in Mogilner and Oster (7)
Saturation value of cross-linking velocity	$v_{\mathrm{g}}^{\text{max}}$	76 nm s−1	Assumed∗† (1)
Saturation length of cross-linking velocity	$\overline{l}$	100 nm	Assumed
Saturation value of polymerization velocity	$v_{\mathrm{p}}^{\text{max}}$	110–150 nm s−1	(51–53)
Total filament density	n	100 μm−1	(11)‡
Orientation angle	θ0	35°	(23,24)
Spring constant of linker	kl	0.7 pN nm−1	(7, 54)
Effective drag coefficient	η	2 pN μm−2	(55)‡
Membrane tension	S	10 pN	Assumed∗‡§ (52)
Retrograde flow	vr	60 nm s−1	Assumed∗†(1)

^∗The ratio k_a/$k_{\mathrm{d}}^0$, S, and $v_{\mathrm{g}}^{\text{max}}$ − v_r were chosen to fit the normal velocity maps in Machacek and Danuser (1). However, the obtained values are close to values given in the above references.

^†Results depend essentially on $v_{\mathrm{g}}^{\text{max}}$ − v_r only, because v_g(l) (Eq. 2) is almost always in the saturation range.

^‡Results depend only on n/η and S/η, not on the absolute values of these parameters.

^§With a lamellipodium height h_l of 176 nm (51) or 200 nm (52), we are close to the value of 0.035 pN nm⁻¹ given in Mogilner and Oster (52) for S/h₁.