MAPK8 and neoplasm: Elevated midkine (MDK) levels have been observed both in tumor biopsies and in the blood serum of HCC patients; thus, it can serve as a biomarker of HCC progression and metastasis via ERK/JNK/p38 MAPK-mediated signaling promoted by ZFAS1, which is elevated in HCC but can be suppressed using microRNA-624 [166].