In the section of “Tether Formation from Neutrophils Treated with Cytochalasin D,” the conclusions drawn from comparing cytochalasin-treated neutrophils with passive ones are partly incorrect due to an error in statistical analysis. The correct conclusions should be: for neutrophils treated with 1 μM cytochalasin D, the threshold force is not statistically different from the value for passive neutrophils p>0.2, but the effective viscosity is p<0.005; for neutrophils treated with 100 μM cytochalasin D, both the threshold force and effective viscosity are statistically different from the values for passive neutrophils (p<0.001 in both cases). Other conclusions in this section remain the same. Consequently, in the Discussion section, the fourth paragraph should read “Cytochalasin D decreased the effective viscosity to the same level as IL-8 and PMA did. It also decreased the threshold force significantly… . The nonzero threshold force suggests that the neutrophil membrane itself does have a significant contribution to the cortical tension, which is about 24–35 pN/μm for passive neutrophils [11,14].” We regret any inconvenience this may have caused.