COL1A1 and ovarian cancer: CAFs are the major stromal cells that produce ECM, and excessive production of fibrillar ECM proteins and ECM remodeling by CAFs in the TME leads to cancer fibrosis.[17] Thereby, we examined CAF‐associated markers expression by immunofluorescence and observed that α‐SMA, FAP, and COL1A1 were significantly decreased in ovarian cancer CAFs under 0.05 μm HF treatment (Figure 4A; Figure S10A, Supporting Information).