DPP4 and neoplasm: Nonetheless, in early tumours the most prominent difference between 4T1 and 4T07 is observed in the CD26 single positive CAFs (5.8% vs 14.4%, respectively), while the PDGFRα single positive CAFs nearly vanish in 4T1 tumours, as compared to 4T07 tumours (1.5% vs 13.7%, respectively), see Table 5.