Fig. 1.

Quantitative macropinocytosis assay and assessment of specificity (A) EGF induces macropinosome formation: Cells were serum-starved for 16 h and incubated with 100 μg/ml dextran–TMR in the presence or absence of 100 ng/mL EGF for 5 min at 37 °C before fixation. MP – macropinosomes; FCS – Foetal Calf Serum and (B) Amiloride inhibits macropinocytosis: Cells were treated with either 1 mM 5-(N-ethyl-N- isopropyl)amiloride (EIPA) or the carrier (0.6% methanol) for 30 min at 37 °C prior the pulse with dextran–TMR (as in A) in the continued absence of the drug or the carrier. The average number of macropinosomes per 100 cells were quantified using the automated image analysis. Error bars represent standard error of the mean (SEM) across three technical replicates of 500 cells per each group.