MAPK3 and metastatic malignant neoplasm in the lymph nodes: As shown in Table 2, the frequency of samples staining positive for p-ERK1/2 and PI3-K in cases with small tumor size (<2 cm in diameter), without lymph node metastasis, and no invasion of surrounding tissues was significantly lower than in cases with larger tumor size (>2 cm), lymph node metastasis, and invasion in surrounding tissues (P < 0.05 or P < 0.01).