According to the following graph, which shows the elongation rate at the plus and minus ends of actin filaments as a function of actin subunit concentration, at what concentration (A to E) does the total length of the filament remain more or less constant with time (i.e. steady-state treadmilling occurs)?

In the polymerization in vitro of actin filaments and microtubules from their subunits, what does the "lag phase" correspond to?

Consider the ATP-bound and ADP-bound forms of actin and the polarized nature of the actin filaments. In the following diagram that shows the various actin polymerization rate constants (k?n and k?ff values), which monomer corresponds to an ADP-bound actin incorporated at the plus end?