TABLE 1.

Features of four different methods to evaluate microtubule rigidity

Methods	Process	Analysis	Working force on MT (P)	Force balance	Force direction	Number of force fulcrums	Manipulation force
Buckling force	Static	Classical mechanics	Compressive force	P = F (keep buckling)	P = F	Two points	Optical trap(s)
Hydrodynamic flow	Static	Hydrodynamics	Hydrodynamic drag force	P(s) = F(s) (keep bending)	P(s) = F(s)	Continuous	Fluid flow
Relaxation	Dynamic	Hydrodynamics	Hydrodynamic drag force	P(s,t) < F(s,t) (relaxation)	P(s,t) = F(s,t)	Continuous	Optical trap
Thermal fluctuation	Dynamic	Statistical mechanics	Thermal force + Hydrodynamic drag force	P(s,t) > F(s,t) (bending) P(s,t) = F(s,t) P(s,t) < F(s,t) (relaxation)	P(s,t) ≠ F(s,t) P(s,t) = F(s,t)	Continuous	Nothing

The value s is the distance along a microtubule, and t is the time.