BCR and B-cell chronic lymphocytic leukemia: Cell-intrinsic pressures may be caused by presence of driver mutations such as KRas(G12D) described for colorectal adenoma to carcinoma progression [122], whereas with tumour microenvironment CLL clones that are less able to take advantage of its ability to provide engagement of BCR, which is a key driver of CLL clonal expansion [11], are more likely to manifest as indolent disease [37].