These networks revealed the regulatory roles of several piRNA in critical genes, including MYC, BCL2, STAT5A, PAX2, IL1R1, COL4A5 and MAP2K6, which are key components of cancer-related pathways, such as TGF-beta signaling, p38 MAPK, ErbB signaling, focal adhesions, and other pathways associated with DNA damage and immune responses. Here, COL4A5 is linked to cancer.