ALDH1A1 and neoplasm: Compared to RT112, monolayers of 5637 cells show higher levels of some markers of stemness, and invasiveness, typically linked to tumor malignancy [49,50], namely a higher positivity to the fluorescent dye AldefluorTM (Figure 2a), a readout of the expression of ALDH1A1 [51,52], and in expression level of the transmembrane glycoprotein CD44 [53,54] (Figure 2b), but not of CD133 [55,56] (Figure 2c).