BCL2L1 and neoplasm: Interestingly, this mode of up-regulating Bcl-xL did not affect the incidence of apoptotic cells in the tumors, in contradistinction to the aforementioned study in which the RIP-Bcl-xL transgene produced a decreased apoptotic index [15]; such phenotypic differences may be explained by differences in the uniformity, timing or levels of expression of Bcl-xL (the effect of the transgene-mediated over-expression of Bcl-xL on tumor invasion was not assessed in this earlier study).