ACTA1 and cancer: Fibroblasts positive for α-SMA and MCT4 are considered to be CAFs.23,24 Catabolic CAFs (MCT4-positive) are known to play an important role in enabling cancer cell propagation, survival, and systemic dissemination during metastasis.25 FN is primarily synthesized by CAFs and deposits into the ECM that acts as scaffold for molecules such as growth factors and cell surface receptors.26 Due to the same distribution of FN and CAFs on the interface of cancer colony and matrix, we believe that the linear FN was produced by the CAFs.