As depicted in Figure 2B, the intracellular concentration of MTX-211 in S1-MI-80 cancer cells (5.92 ± 0.69 pmoles/μL) was notably lower than that in the parental S1 cancer cells (19.9 ± 0.95 pmoles/μL), a phenomenon that was susceptible to restoration by blocking the function of ABCG2 with Ko143. Here, ABCG2 is linked to cancer.