Type XII collagen is elevated in serum from patients with solid tumors: a non-invasive biomarker of activated fibroblasts.

Understanding the tumor microenvironment (TME) and extracellular matrix (ECM) is crucial in cancer research due to their impact on tumor progression. Collagens, major ECM components, regulate cell signaling and behavior. Of the 28 reported collagens, type XII collagen is known to be vital for ECM organization.