COL1A1 and breast cancer: As shown in Figures 5A, E, 4-OHA decreased the components of ECM in breast cancer cells by downregulating the expression levels of ECM-related genes, such as Col1a1, Tnc, Fn1, and Itga5. Moreover, these ECM-related genes play a role in the PI3K-Akt signaling pathway (20, 23, 24).