The malignant transformation includes many genetic changes, including those rendering the malignant cells capable of invasion and metastases. CD44 plays a role in cell adhesion and enables malignant cells to metastasize. Solid tumors can express CD44 to enhance their spread to lymph nodes and other metastatic sites. Though such properties may have been present with the initial clone of malignant cells, the growth of cancer increases the number of cells and the risk for spread. BCL2 plays a role in apoptosis. Growth factor receptor expression may make malignant cells susceptible to environmental influences, such as hormones, that drive growth. RAS gene mutations are present in many cancers and lead to loss of growth control. Vimentin is best known as a protein expressed in mesenchymal neoplasms, such as sarcomas, but it is also up-regulated in EMT.