The result showed that the level of the activation state of Rac1 (Rac1-GTP) was significantly increased at 10 min after HFS (one-way ANOVA, F(3, 8) = 63.24, control group, 0.19 ± 0.029, n = 3; 10-min group, 0.84 ± 0.033, n = 3; P < 0.0001; Figure 1A), but returned to control level at 30 min after HFS (one-way ANOVA, 30-min group, 0.30 ± 0.055, n = 3, vs. control group; P = 0.1974; Figure 1A). This evidence concerns the gene RAC1 and Hand-foot syndrome.