RB1 and neoplasm: Five groups of H22 tumor-bearing mice with tumor volumes of approximately 150 mm3 were injected intratumorally with PBS, PLGA-RB-FLuc nanoparticles, PLGA-RB nanoparticles plus luciferin, PLGA-RB nanoparticles (plus external light irradiation), or PLGA-RB-FLuc nanoparticles plus luciferin.