ABCG2 and cancer: To further confirm the role of PFKFB4 in cancer stemness-related chemoresistance, we investigated the expression of several cancer stemness markers, namely CD44, CD166, ABCG2, ALDH1A1, ALDH1A2, and EpCAM and found that their expressions were lower in PFKFB4–knocked down SAS and TW2.6 cells than scramble cells (Fig. 5C).