COL1A1 and cancer: In addition, fibroblasts (n = 1 068) were identified by COL1A1 and FAP, endothelial cells (n = 2 561) were positive for RAMP2 and CLDN5 expression, smooth muscle cells (n = 1 100) were defined by TAGLN and CNN1, and epithelial/cancer cells (n = 319) were labeled by KRT14 and KRT17 (Fig. 1b, c).