Cell lines were cultured in the presence or absence of anti–Erb-B2 IT at the indicated concentrations for 4 days. Subsequently, cells were washed twice in PBS, reseeded into 96-well plates at 10 or 30 events per well by the automatic cell deposition unit of a flow cytometer as described in Materials and Methods, and incubated for 30 days in optimal growth medium (DMEM containing 10% FCS).

Data are represented as the number of positive wells, ie, wells containing at least 1 cluster of >30 cells per total number of wells seeded.