H-CAFs are pathologically activated in tumors, whereas NSFs and PTFs remain inactivated.

(A) Microscope images of H-CAFs, PTFs and NSFs incubated for 24 hours. When originally isolated from the tumor specimens, PTFs and NLFs presented with a static, pericyte-like phenotype, whereas H-CAFs harbored an activated phenotype resembling myofibroblasts. (B) The expression of α-SMA, FAP, FSP and fibronectin in H-CAFs, PTFs and NSFs incubated for 24 hours was determined by immunofluorescence staining. α-SMA expression was remarkably higher in H-CAFs and relatively non-existent in the other fibroblast types when analyzed immediately following harvest from tumor specimens. This difference suggests the pathologically activated nature of H-CAFs and the relatively static nature of the other fibroblasts within the original tissues.