CD44 and neoplasm: Figure 2A displays that FLRT2 was successfully overexpressed in A549 and H1975 stem cells. Tumor sphere-formation data revealed that cells in the FLRT2 group had significantly lower sphere-forming ability than cells in the control group (Figures 2B, C). FLRT2 upregulation decreased the protein and mRNA levels of stem cell markers OCT4, CD44, and CD133 in A549 and H1975 stem cells (Figures 2D, E).