Given that enhanced EGFR phosphorylation activates multiple downstream signaling pathways, including the MAPK-ERK, the PI3K-AKT, the JAK-STAT3, and the NF-κB [45–48], all of which play critical roles in cancer cell proliferation and migration, we investigated the activation of these pathways in response to circUCK2(2,3) knockdown or overexpression. This evidence concerns the gene MAPK1 and cancer.