<b>A:</b> Identification of subpopulations of cells in HNSCC cell lines.

<p>Dot plot analysis of LK0923, LK0827 and LK0863 cells co-stained with an APC-conjugated anti-CD44 antibody and a PE-conjugated anti-epidermal growth factor receptor (EGFR) antibody. The red colored areas represent the CD44^high cells, and the three boxes display the gating of the different subpopulations from which cells were isolated for further experiments. <b>B:</b> Light microscope images of CD44^low, CD44^high/EGFR^high and CD44^high/EGFR^low populations (3 days after sorting) and unsorted LK0923, LK0827 and LK0863 cell cultures.