Table 1. Comparison of actin assembly rates in the presence of formin.

Conditions*	Barbed end rate, s1/frequency, %	Pointed end rate, s-1/frequency, %
Filaments + actin	10.2 ± 0.2/100	0.38 ± 0.07/100
Filaments + actin + 10 nM	0.0 ± 0.0/95	0.44 ± 0.15/100
Cdc12(FH1FH2)p	13.2 ± 0.3/5	0.38 ± 0.03/100†‡
Filaments + actin + 25 nM	11.4 ± 0.1/100	0.30 ± 0.04/100
Bni1(FH1FH2)p	6.9 ± 0.2/100†§	0.39 ± 0.04/100†
Actin	11.2 ± 0.8/100	0.35 ± 0.04/100
Actin + profilin	12.1 ± 0.5/100	0.03 ± 0.05/100¶
Actin + 20 nM	0.0 ± 0.0/> 99	0.39 ± 0.04/100‡
Cdc12(FH1FH2)p	10.6 ± 0.2/< 1
Actin + 20 nM	7.4 ± 0.3/100∥	0.05 ± 0.05/100¶
Cdc12(FH1FH2)p + profilin
Actin + 20 nM Bni1(FH1FH2)p	7.5 ± 0.2/100§	0.23 ± 0.03/100
Actin + 20 nM Bni1(FH1FH2)p + profilin	10.1 ± 0.3/100**	0.05 ± 0.06/100¶

^*Experiments where formin was not attached to the slide surface, as reported in Figs. 1 and 5. Twenty individual filaments were measured from two independent experiments.

^†Freshly nucleated filaments.

^‡The rate that Cdc12(FH1FH2)p-nucleated filaments assembled was not statistically different from the rate of control pointed ends, by the two-tailed t test (P = 0.433-0.612).

^§Bni1(FH1FH2)p-nucleated filaments grew significantly slower at their barbed ends than control barbed ends (P < 0.002).

^¶In the presence of profilin, Cdc12(FH1FH2)p-nucleated barbed ends grew significantly slower than control barbed ends (P = 0.0006).

^∥Profilin forced pointed ends to grow significantly slower than control pointed ends (P < 0.0001).

^**In the presence of profilin, Bni1(FH1FH2)p-nucleated barbed ends grew significantly faster than in the absence of profilin (P = 0.0002), but not statistically different from control barbed ends (P = 0.752).