Complex sentence: For example, cell membrane integrins on circulating leukocytes are maintained in an inactive state to avoid epithelial cell attachment; they are only activated in response to stimuli such as those received at the site of an inflammatory response.
Split into simpler sentences: For example, cell-surface integrins on circulating leukocytes are maintained in an inactive state to avoid epithelial cell attachment. Only in response to appropriate stimuli are leukocyte integrins converted into an active form, such as those received at the site of an inflammatory response.