All mutations identified in PDXs were confirmed in parental tumours, with the exception of LT267 (human tumour mutated in TP53, KRAS, PIK3CA and SMARCB1, whereas PDX was mutated in KRAS and PIK3CA only, Fig. 2A), with a general increase in the frequency of mutated alleles being observed in LcPDXs. The gene discussed is KRAS; the disease is neoplasm.