MMP1 and liver cancer: For example, circPIP5K1A activates the PI3K-Akt signaling pathway through sponge adsorption of miR-671-5P, thereby promoting the progression of gastric cancer [21]; the circRNA circDLC1 inhibits MMP1-mediated liver cancer progression via interaction with HuR [22]; and exosomal circRNA-100338 promotes HCC metastasis via enhancing invasion and angiogenesis [23].