Considering the gefitinib concentration in NSCLC tumor tissues is more than 40-fold higher than plasma levels, we speculate that ABCC10 may play a more important role than ABCG2 in acquired resistance to gefitinib in vivo (McKillop et al., 2005; Haura et al., 2010). Here, ABCG2 is linked to non-small cell lung carcinoma.