The contact between CLL B cells and MSCs induces dramatic gene expression modifications (94, 95), including an increase in antiapoptotic molecules such as B cell lymphoma 2 (BCL2) (96, 97), B cell lymphoma-extra large (BCL-XL) (96, 98), myeloid leukemia cell differentiation protein 1 (MCL1) (67, 71, 98), and β-catenin (95), as well as soluble factors that will be discussed below. Here, MCL1 is linked to B-cell chronic lymphocytic leukemia.