ABCG2 and neoplasm: As for human Non-Small Cell Lung Cancer (NSCLC) cell lines, the presence of a Hoechst dye 33342 extruding in SP cells, which accounted for 0.03 - 6.1% of the tumor cells [8], have shown elevated expression of ABCG2, increased tumorigenicity in mice, and resistance to various chemotherapeutic agents [9].