To explore the mechanism of RPS27a up-regulation in the transition from CML-CP to CML-AP/BP, We hypothesized that some highly expressed proteins (P- gp, AXL, Hsp-70, STAT3, STAT5, CIP2A, BMI-1 and ABCG2) in imatinib resistant CML cells contributed to the up-regulation of RPS27a gene. This evidence concerns the gene ABCG2 and chronic myelogenous leukemia, BCR-ABL1 positive.