ACTA1 and neoplasm: Cell populations isolated from tumor tissue samples are defined as CAFs when they have an elongated spindle morphology, negative staining for non-mesenchymal biomarkers, and positive staining for mesenchymal biomarkers such as podoplanin (PDPN), CD29, alpha-smooth muscle actin (αSMA), fibroblast activation protein (FAP), and platelet-derived growth factor beta (PDGFβ) (Costa et al., 2018; Han et al., 2020).