Ye et al (2001) examined the role of PTHrP in tumour growth and progression in a colon cancer cell line and demonstrated that overexpression of PTHrP in HT29 cells caused an increase in cell adhesion to the extracellular matrix (ECM) protein collagen type I. Adhesion to fibronectin and laminin was unaffected which led the authors to suggest that this selective increase in adhesion facilitated tumour cell metastasis to specific organs. This evidence concerns the gene PTHLH and malignant colon neoplasm.