In vitro assays showed that the mechanism of IL-19 in 4T1 cells is activating the intracellular signals STAT3, JNK, ERK, AKT, and NF-κb, which may be involved in cell proliferation and survival, but phosphorylation occurred only on JNK, ERK, and AKT in Hs578T human breast cancer cells [13]. Here, MAPK8 is linked to breast cancer.