Unlike the lines with forced expression of E2F1, 2 or 3, cell lines transduced with E2F4, E2F5 and E2F6 did not continue to grow following serum withdrawal, and maintained cell numbers equal to or less than the control-transduced cultures throughout the entire response (Figure 3 B, open symbols).
The correct positioning of the CD4+ dendritic cells was, in turn, necessary for maintaining cell numbers.
On the other hand, the rostral increase in proliferation could be a mechanism to compensate for cell death and to maintain cell numbers in the rostral DG.
The occurrence of lymphopenia-induced proliferation in rodents (Miller & Stutman, 1984; Bell et al., 1987; Freitas & Rocha, 2000) has suggested that the immune system has an intrinsic capacity to maintain cell numbers at sufficiently high levels by inducing a compensatory homeostatic response when cell numbers are low.
Cell number and chondrogenic phenotype (CD14 CD90 ratios) were found to decline in regions with a higher storage modulus (>13,100 Pa), while regions with a lower storage modulus maintained their cell number and phenotype.
Two independent studies have demonstrated that transgenic expression of Bcl2 maintains NK cell number in IL15−/− mice and that IL15 is important for NK cell survival[15], [16].
Self-renewal and proliferative abilities are essential for maintaining stem cell number and preventing tissue dystrophy.
Because the product of an asymmetric self-renewal division is one stem cell and one differentiated cell, this process maintains stem cell number.
Apoptosis plays a fundamental role in animal development, by sculpting tissues and structures, as well as in tissue homeostasis, by regulating and maintaining balanced cell number [ 4- 6].
Therefore cell cycling rate may be reduced to the level sufficient to maintain the cell number and this may account for the down-regulation of some of the SW-abundant genes (casp6, cdc45 variant 1, ccnb1, msh2, ercc6) that are associated with cell cycle, DNA replication and repair.
