ID3 knockdown by shRNA and inhibition of tumor seeding in vivo. (A) Representative live in vivo imaging of implanted D283 cells transfected with either control-shRNA or ID3-shRNA for 28 days. Note the migration of signals along the spinal cord of a mouse injected with D283-control-shRNA. (B) Serial measurement of tumor-occupied areas in live in vivo imaging. (C) Serial measurement of the longitudinal extent of tumors from the cranium to the spinal canal. (D) Representative gross photos of mice injected with PBS, D283-controlshRNA, and D283-ID3-shRNA. Mice that received D283-control-shRNA (middle photo) show cachexia and scoliosis, signs of tumor seeding along the spinal cord. (E) A Kaplan-Meier survival plot of mice after implantation of D283 cells reveals the increased survival by shRNA. All animals were sacrificed at day 28 for histological examination.