Figure 3. Angiopep-2 polypeptide-modified and doxorubicin-loaded graphene oxide (ANG-Dox-GO) inhibits tumor growth in U87 MG cells. (A) Cell viability of U87 MG cells treated with PBS (control), GO, Dox (30 μg/mL), Dox-GO (containing 30 μg/mL of Dox), and ANG-Dox-GO (containing 30 μg/mL of Dox), respectively, for 24 h and 48 h by MTT assay. (B) Clone number of U87 MG cells treated with PBS (control), GO, Dox (30 μg/mL), Dox-GO (containing 30 μg/mL of Dox), and ANG-Dox-GO (containing 30 μg/mL of Dox), respectively, for 24 h by colony formation assay. *P < 0.05 vs control cells; #P < 0.05 vs Dox; &P < 0.05 vs. Dox-GO.