Figure 2. GD2 identifies CD44^hiCD24^lo stem cell phenotype in breast cancer cells.

(A) HMLER cells were stained with anti-GD2 antibody and with CD44-APC and CD24-FITC using the 4-step staining protocol described in Methods. Cells were electrically gated on GD2^+/– cells and displayed in a pseudocolor dot plot with CD44 on the y axis and CD24 on the x axis using FlowJo data analysis software. (B) In an identical experiment, CD44^hi/loCD24^lo/hi cells were displayed on a pseudocolor dot plot with GD2 on the y axis and FSC on the x axis. (C) Primary breast tumor samples were processed as described in Methods, and the single cells in suspension were stained with anti-GD2, CD44-APC, CD24-FITC, CD45-FITC, and DAPI using the 4-step staining protocol. Cells were initially gated on DAPI-negative cells to exclude dead cells, and the cells were then gated on CD45^– cells to exclude hematopoietic cells. GD2⁺CD45^– cells were displayed on a dot plot, with CD44 on the y axis and CD24 on the x axis. Analysis was perfumed using an LSR II flow cytometer. Data were analyzed using FlowJo software.