Maletzki C. et al. engrafted four different individual colorectal (CRC) PDX models into NOD.Cg-PrkdcscidIl2rgtm1Wjl (NSG) mice and treated them with a cytostatic drug, 5-fluoruracil (5-FU) [37]. The gene discussed is CTSG; the disease is colorectal carcinoma.