Length of simulated spindles scales with catastrophe rate and minus-end depolymerization activity. (A and B) Range of steady-state spindle structures obtained with different MT plus-end catastrophe frequencies (mean ± SD, 95 simulations). (C and D) Range of steady-state spindle structures obtained with different MT minus-end depolymerization rates (mean ± SD, 126 simulations). In A–D, the text or symbol color designates bipolarity index: astral (red), bipolar (yellow), strongly bipolar (green).