Furthermore, in a bid to delineate the association between TMZ-resistance, CD133 positivity, and DRD4 expression, using the xenograft murine GBM models, we demonstrated that compared to the 33.3% (n = 3) tumorigenicity observed in litter-mates inoculated with parental U87MG cells, all the mice (n = 3) inoculated with CD133+ TMZ-resistant cells recorded tumor formation by day 21 (Figure 2E). The gene discussed is DRD4; the disease is glioblastoma.