Zetiq has introduced a histochemical stain that claims to tinctorially identify cancer and neoplastic cells. Because of the potential importance of such a capability, the investigators undertook to investigate Zetiq's CellDetect® staining technology as applied to cultured cell lines as well as an initial sample of clinical cases. This goal was pursued by investigating four types of comparisons: 1) cancer cell lines before and after differentiation; 2) cervical squamous-cell carcinoma (SCC) biopsies to non-neoplastic squamous epithelium; 3) SCCs to neoplastic, nonmalignant squamous epithelium; and 4) neoplastic squamous cells to non-neoplastic squamous cells in cytological preparations. The clinical material was also stained with hematoxylin and eosin (biopsies) or Pap (cytologies) for diagnostic purposes. The investigators found that all CellDetect®-stained cells exhibited one of the two tinctorial outcomes. Cell lines with malignant phenotype uniformly had red/purple cytoplasm, whereas the differentiated phenotype changed the color to blue/green.