Sorting cells for high or low levels of expression of CD44 showed, as previously indicated for carcinoma-derived cells [21], that the CD44high cell fractions are more clonogenic when plated in standard culture conditions and form a greater proportion of colonies with holoclone morphologies for both malignant and normal keratinocytes (Fig. 1J, 1K and1L, respectively). This evidence concerns the gene CD44 and carcinoma.