While the mechanistic link between miR-198 and FUT8 has not yet been investigated, it has been shown that circular ERBB2 RNA (circ-ERBB2) promotes breast cancer metastatic process, cellular invasion, and proliferation by competing with miR-198 and miR-136-5p as an endogenous RNA sponge (Figure 2) [54,55]. Here, FUT8 is linked to breast cancer.