Although no immunocytochemical staining for Neu or S100A4 was found in the lung tissue of the nude mice bearing mammary gland tumours produced by the 8Neu cell line (not shown), clusters of stained cells forming micrometastases and even single cells were readily discernable in the lungs of mice with tumours produced by the 8Neup9Ka and PN2 cell lines (Figure 5E, L). Here, S100A4 is linked to neoplasm.