ABCG2 and cancer: Spitzwieser et al. have determined promoter methylation levels of ABCB1, ABCC1, and ABCG2 in seven cancer cell lines, including five NSCLC (A549, HCC827, NCI-H520, NCI-H1703, SW 1573) and two SCLC (DMS 114, GLC-4) cell lines [142].