to examine the time-course and rate of appearance of sulfated macromolecules at the cell surface , the cells were pulsed with 35so4 for short periods ( 5-15 min ) , and the incubation medium was sampled for spontaneously released macromolecules ( basal secretions ) and for release induced by trypsin ( trypsin-accessible secretions ) .
C0699040
cell surface
C0007634
cells