To find out whether endogenous OLA1 is related to the development of drug resistance in breast cancer, the endogenic level of OLA1 in both mRNA (Figure 2D) and protein levels (Figure 2E) in MCF-7-PTR was analyzed, and showed that both endogenous levels of mRNA and protein of OLA1 were indeed significantly higher than that of the parental cells (*P< 0.05, **P < 0.01), indicating that OLA1 plays a regulatory role in the development of tumor drug resistance. Here, OLA1 is linked to breast cancer.