POU5F1 and metastatic malignant neoplasm in the lymph nodes: Several studies [15,19,35,37,38,39] have also reported an enhanced expression of the stem cell markers CD44, ALDH1, c-Met, Oct3/4 and SOX-2 in primary tumours of patients with lymph node metastasis compared to those with negative lymph nodes (Table 2), although the differences were not always statistically significant [15].