Figure 5: Soft agar colony formation assay showing the increased tendency of S1 or S1M1-80 cells to form anchorage-independent colonies after a 3-week incubation, which was abolished by knocking down ABCG2 by silencing vector. (a) Silencing efficacy of the ABCG2 shRNA as revealed by Western blot analysis. ABCG2 protein expression was decreased by ~50% in the shRNA-transfected S1M1-80 cells. (b) Relative no. of colonies formed in S1 or S1M1-80 cells after the indicated treatment. 𝑃 < 0 . 0 5 , compared with the no-treatment group.