Fig. 4. Cluster analysis of HER2 proteins in 11 SKBR3 cells.

(A) The pair correlation function g(x) of a total of 14,171 labels exhibited a peak at 20 nm, indicating HER2 dimerization. Larger-sized clusters of up to several hundreds of nanometers were also observed. The curves of randomly dispersed QDs and a simulation (Simu) of random data were included as reference. (B) HER2 pairs were absent in cellular areas with a homogeneous membrane topography, contrasting g(x) in the ruffled areas. (C) HER2 does not appear clustered in the two analyzed flat cells. Clustering was only observable in cells with membrane ruffles.