Knockdown of ABCG2 using siRNAs and inhibition of ABCG2 using Ko143 decreased the SP rate (Fig 5E and 5F), whereas knockdown of ABCG2 and inhibition of ABCG2 did not decrease sphere formation (Fig 5G and 5H), indicating that ABCG2 expression is not related to tumor formation. This evidence concerns the gene ABCG2 and neoplasm.