Mammary gland gestation, serum progesterone remains at a stably high concentration so signaling through its receptor is continuously activated. As one of the transcribed genes, Wnts secreted from mammary epithelial cells act paracrinely to induce more neighboring cells' branching. When the lactiferous duct tree is almost ready, "leaves" alveoli are differentiated from luminal epithelial cells and added at the end of each branch. In late pregnancy and for the first few days after giving birth, colostrum is secreted. Milk secretion (lactation) begins a few days later due to reduction in circulating progesterone and the presence of another important hormone prolactin, which mediates
AKA... What a Life! alongside "If I Had a Gun...", which was released as a North American (digital) single on 31 August 2011. It was later physically released as a CD single, 7" vinyl on 17 October 2011. It reached number twenty on the UK Singles Chart. On 1 September 2011, a minute and thirty second preview of "...What a Life!" was released through a sponsorship commercial by Vauxhall on YouTube, which supposedly gave attention to the commercial. "AKA...What a Life!" is only available for digital download in the United Kingdom and Ireland. Originally the single was to be called "Ride the Tiger" but