ABCG2 and cancer: As shown in Figure 5, we were unable to find any significant changes in the protein level of ABCB1 in KB-V-1 cells (Figure 5a and Figure S1) and NCI-ADR-RES cells (Figure 5b and Figure S2) or ABCG2 in S1-M1-80 cells (Figure 5c and Figure S3) and H460-MX20 cells (Figure 5d and Figure S4), indicating that the down-regulation of ABCB1 and ABCG2 is unlikely to play a major role in the resensitization of multidrug-resistant cancer cells by sitravatinib.