Study by Hosokawa et al., demonstrated that OCT-3/4 expression was well related to ATP binding cassette transporter G2 (ABCG2), a drug efflux pump gene, in glioblastoma samples, and OCT-3/4 could strengthen the resistance of chemotherapeutic drugs, such as doxorubicin, carboplatin, and etoposide phosphate, in glioblastoma cell lines by elevating the expression of ABCG2 [44]. Here, ABCG2 is linked to glioblastoma.