Varied gene expressions between osteosarcoma cells grown in 3D compared to 2D models potentially contribute to drug sensitivity differences including upregulation of the ATP-binding cassette transport genes (ABC-B1, -C1, and -G2) implicated in drug efflux [13], multiple drug resistance protein 1 (MDR-1) [69]. The gene discussed is ABCB1; the disease is osteosarcoma.