PRG4 and neoplasm: However, the BAI3, GNAS, PRG4, and OBSCN genes showed different patterns of mutation frequency between PDX models and patients such that BAI3 and GNAS genes showed relatively higher mutation frequencies in the tumor samples from the patients (11 and 11%, respectively) compared with those in the tumor samples from the PDX models (8 and 10%, respectively), and conversely PRG4 and OBSCN genes showed higher mutation frequencies in the tumor samples from PDX models (21 and 15%, respectively) compared with those in the tumor samples from the patients (8 and 8%, respectively) (Fig. 2b).