ABCG2 and cancer: However, we found that citarinostat had a significantly reduced effect on HDAC6 in ABCB1-overexpressing KB-V-1 (Figure 2A, right panels) and ABCG2-overexpressing S1-M1-80 (Figure 2B, right panels) cancer cells as compared to the respective parental KB-3-1 (Figure 2A, left panels) and S1 (Figure 2B, left panels) cancer cells.