To investigate which signal transduction pathways regulated high expression of JAM-A in HNSCC, the Detroit562 cells were treated with various inhibitors of signaling pathways, GF109203X (PKC inhibitor), LY294002 (PI3K inhibitor), U0126 (MAPK inhibitor), iGSK-3β (Wnt inhibitor), AG1478 (EGFR inhibitor), SB203580 (p38 MAPK inhibitor), SP600125 (JNK inhibitor) and cyclopamine (Hedgehog inhibitor). Here, MAPK8 is linked to head and neck squamous cell carcinoma.