DDR1 and cancer: The increased collagen deposition can ligate their corresponding surface receptors [e.g., the discoidin domain receptor (DDR) family of receptor tyrosine kinases and certain types of integrin (e.g., α1β1, α2β1, α10β1, and α11β1)] of cancer cells.8 DDR, composed of two members, DDR1 and DDR2, regulates downstream molecules (e.g., STAT3, STAT5),9 which eventually coordinates cell adhesion, migration, proliferation, and matrix remodeling.9