Gain of Bcl-2 is more potent than Bax loss in regulating mammary epithelial cell survival in vivo

The impact of gain of Bcl-2 function on mammary epithelial cell survival wa s compared with loss of Pax function during the two stages of mammary gland involution. Bcl-2 gain of function reduced apoptosis 50% during the first stage and increased cell survival 70% during the second stage. Complete los s of Pax reduced apoptosis by 20% during the first stage without second sta ge effect. Partial loss of Bar was ineffective but increased cell survival 2,4-fold when combined with Bcl-2 gain. Gain of Bcl-2 function is more pote nt than loss of Bar function in regulating mammary epithelial cell survival irt vivo.