The emerging role of CD44 in regulating skeletal micrometastasis.

The hyaluronan (HA) receptor CD44 has a well documented role in tumour metastasis. This review focuses on the potential significance of CD44 expression and function in regulating the metastasis of both haematological malignancies and solid tumours to the bone. Specifically, the review will discuss the evidence that HA-CD44 interactions facilitate the arrest of circulating malignant cells upon the bone marrow endothelial cells and discuss data that suggests CD44 may orchestrate the ability of tumour cells to regulate the modification of the bone matrix and support its colonisation by malignant cells.