title: Effects of cytochalasin B and enucleation on EGF receptor down regulation.
abstract: The loss of epidermal growth factor (EGF) binding activity on cultured murine 3T3 cells exposed to EGF (EGF receptor down regulation) was determined in colchicine treated cells, cytochalasin B treated cells, and untreated cells. Neither colchicine nor cytochalasin B altered the affinity of the receptor for EGF, but colchicine decreased maximal EGF binding activity by 20%. The maximal extent of EGF receptor down regulation was similar in colchicine treated cells and cytochalasin B treated cells, but the rate of receptor down regulation was higher in cytochalasin B treated cells. Cytoplasts produced by subjecting cytochalasin B treated cells adhering to the substratum to centrifugal force responded to EGF with nearly normal down regulation kinetics. The results suggest that the cytoskeleton is not obligatorily involved in EGF-induced EGF receptor down regulation.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000502:physiology; D002478:Cells, Cultured; D003078:Colchicine / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology*; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors; D008297:Male; D051379:Mice; D010455:Peptides / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*
chemical_list: D010455:Peptides; D011956:Receptors, Cell Surface; D003571:Cytochalasin B; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D003078:Colchicine