The present study investigated whether spheroid body-forming cells in the human gastric cancer (GC) MKN-45 cell line are enriched for CSC properties, and also assessed the expression of the candidate CSC markers, octamer-binding transcription factor-4 (OCT4) and adenosine triphosphate-binding cassette transporter G2 (ABCG2) in the MKN-45 spheroid body cells. This evidence concerns the gene ABCG2 and gastric cancer.