Figure 2. Role of circular RNA of circAMOTL1 expression in drug resistance. (A) The expression of circAMOTL1 in immortalized normal cells BEAS-2B and HaCaT, and cancer cells MDA-MB-231, MCF-7, HepG2 and SNU449 were examined using real-time PCR (n=4). **p<0.01 compared to BEAS-2B cells. (B) The expression of circAMOTL1 was shown in agarose gel after the MDA-MB-231 cells were transfected with circAMOTL1 plasmids or vector control. (C) The existence of circAMOTL1 was validated by Sanger sequencing. Red arrow represents “head to tail” junction of circAMOTL1. (D) The overexpression of circAMOTL1 was validated by qPCR in the MDA-MB-231 and HepG2 cells. n=6. **p<0.01 compared to vector control. MDA-MB-231 cells transfected with vector or circAMOTL1 plasmids were treated with different concentrations of PAX (E), epirubicin (F), or cyclophosphamide (G) for 24 hours, respectively. Chemoresistance was shown by cell viability. n=3 for each treatment. **p<0.01 compared to untreated cells.