The higher cellularity in the bone marrow of 92R- and Srb1-treated animals is due to endogenous cells and might simply be the consequence of a decrease in bone marrow cellularity on the isotype control treated animals, since the tumor cells, with a 4 to 5-fold larger volume than the endogenous bone marrow cells, have successfully replaced a large fraction of the endogenous bone marrow precursors, while competing for a restricted space, reducing the ability of the bone marrow to produce red blood cells and platelets, as it has been described to occur in humans (40). This evidence concerns the gene SCARB1 and neoplasm.