The difference in metastasis potential between these cell lines was sharply correlated with the number of PGC-like tumor cells present in these cell lines, as determined by non-specific alkaline phosphatase (AP) staining, which is used for the identification of PGCs since AP is a maker for PGCs10 (Fig. 2e) and other PGC marker gene expression (Fig. 2f), indicating that PGC-like cells may play a crucial role in liver metastasis. Here, PGC is linked to neoplasm.