Before revision:  Fisher and Anatoly B. Kolomeisky (PNAS(2001) 98(14) P7748-7753) . Generally, the formulation of the velocity of molecular motors can be obtained .
After revision:  Fisher and Anatoly B. Kolomeisky (PNAS(2001) 98(14) P7748-7753) , we are able to obtain an explicit formula for the velocity of a molecular motor .