Similarly, mTOR inhibitor rapamycin chemically conjugated to HA nanoparticles via a novel sustained-release linker, 3-amino-4-methoxy-benzoic acid was found to slow down the clearance of rapamycin by 8.8-fold in immunocompetent mice bearing CD44-positive 4T1.2neu breast cancer cells. The gene discussed is CD44; the disease is breast carcinoma.