(A) Images showing fluorescently labeled, plus-end capped F-actin (5 µM) to which either HMP-1 (5 µM), UNC-94 (2.5 µM) or both have been added. Note that actin bundles form only when HMP-1 is present and that UNC-94 can lengthen HMP-1-generated actin bundles. Bar = 10 µm. (B) (Left) Histogram of actin bundle length when HMP-1 is added alone (n=663) or together with UNC-94 (n=603). Percentage of bundles exhibiting particular lengths (indicated in µm) is shown. The bracket indicates that when HMP-1 and UNC-94 are added together, there is an increase in the longest population of bundles filaments. (Right) Mean length of actin bundles formed by HMP-1 alone and HMP-1 plus UNC-94. Error bars, SEM. Actin bundles generated by HMP-1 plus UNC-94 are significantly longer than those generated by HMP-1 alone (p < 0.001, two tailed t-test).