Significantly, the concomitant presenceof the ALDEFLUOR-positive phenotype and of the previously described breast CSCphenotype (CD44+/CD24−/low) was observed in a small cellfraction of the three triple-negative tumors (range 0.08–1.16%), whereas tumorcells generated from one metastatic tumor (pleural effusion) showed a highpercentage of overlapping cell fraction (1.16%) that gave rise to outgrowth fromas few as 20 cells. Here, CD44 is linked to Pleural effusion.