The role of the cytoskeletal structure on the shear tolerance of hybridoma and insect cells to laminar and turbulent shear flow field was investigated. The cytoskeletal network of cells modified by taxol and diamide, which are known to alter the stability of specific cytoskeletal components, resulted in increased cell shear tolerance to both laminar and turbulent flow fields. Plasma membrane fluidity measurements revealed that modification of microtubules by taxol did not alter the fluidity state of the plasma membrane. The increase in shear tolerance by taxol treatment is attributed to its ability to stabilize microtubules in the cytoskeleton. A low concentration of taxol, 0.05 microM, did not reduce the hybridoma cell growth rate or the monoclonal antibody production rate, but both were decreased at a higher concentration, 0.25 microM.