As shown in Fig. 4d, adding CHI3L1 protein to gastric cancer cell (MKN-45 and AGS) and breast cancer cell (MDA-MB-231, MDA-MB-435, and MDA-MB-468) cultures promoted the phosphorylation of ERK and JNK but not Src and AKT, which was abolished by IL-13Rα2 gene silencing in cancer cells. Here, MAPK8 is linked to breast cancer.