PDPN and breast cancer: On the other hand, it has been recognized that CAFs constitute heterogeneous subpopulations with distinct molecular characteristics (Cully, 2018; Davidson et al., 2021; Sebastian et al., 2020; Sidaway, 2018) and the relative function of specific biomarkers is likely to vary by tumor type and has yet to be defined fully, e.g., the impact of podoplanin (PDPN) on the function of CAFs is controversial for breast cancer and lung cancer (Takahashi et al., 2015), the impact of different CAF subtypes on patient outcomes is a topic worth studying.