dependent cell-adhesion proteins that mediate cell-cell interaction, and several cadherins are expressed in mammary gland alveolar buds and terminal end buds. Previous research has indicated that disruption of cell-cell contacts inhibits forward growth, suggesting that these interactions are essential for proper mammary gland growth through the fat pad [26]. It is possible that aberrant signaling in the absence of Akt1 disrupted cell-cell signaling, resulting in improper growth, as demonstrated in the delayed ductal outgrowth and deficiency in terminal end bud growth and alveolar bud development. Collectively, our findings suggest that Akt signaling is essential for proper alveolar bud apoptosis, quantity, growth, and size. Considering prior studies and our novel findings, it is likely that Akt1 is necessary for both proper mammary gland postnatal growth and functional adult development. Regarding postnatal growth, Akt1 appears essential for ductal outgrowth through the fat pad as well as for the bifurcation of terminal end buds and formation of alveolar buds and terminal ducts. Permanent changes in mammary gland composition and gene expression are likely contributing factors to the abnormal function of adult Akt12/2 mammary glands. Regarding Btn1a1, it seems that Akt1 is essential for its expression both during a basal virgin state as well as during pseudopregnancy. The lack of Btn1a1 and Akt1 expression, both of which influence milk lipid production, can result in increased offspring mortality, suggesting these genes are essential for proper reproductive health and offspring growth. References 1. Sternlicht MD (2006) Key stages in mammary gland development: the cues that regulate ductal branching morphogenesis. Breast Cancer Research 8: 201. 2. Richert MM, Schwertfeger KL, Ryder JW, Anderson SM (2000) An atlas of mouse mammary gland development. 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PLoS ONE | www.plosone.org 11 September 2011 | Volume 6 | Issue 9 | e24432