Total EGFR level is not impacted by LKB1.
A, representative images from confocal microscopy for total EGFR (red). The nucleus was stained with DAPI (blue). Both LKB1 and LacZ-transfected A549 cells displayed similar distribution of EGFR under non-stimulatory and EGF-stimulated conditions (scale bar, 5 μm). B and C, as measured by flow cytometry, under non-stimulatory conditions, total EGFR expression in LacZ and LKB1-treated cells remained the same (unpaired t test, p = 0.9912). D, Rh-EGF binding of cell surface EGF receptors is similar in LacZ and LKB1-treated cells. Binding curve and Scatchard plot (inset) represent mean fluorescent intensities. Both LacZ and LKB1-treated cells show similar binding curves as well as biochemical parameters (Bmax, 1700 and 1615; Kd, 0.0040 and 0.0045 nm for LacZ and LKB1, respectively). E, binding of Rh-EGF was assessed at various time points after stimulation with unlabeled EGF. LacZ and LKB1-treated cells showed similar recycling kinetics, peaking within 30 to 60 min. NT, no treatment; Unst., unstained; IgG ctr, IgG control.