WP2815 - Mammary gland development: involution - stage 4 of 4 - Homo sapiens

After pregnancy and lactation, the mammary gland undergoes a tissue remodeling process, known as involution. This process is characterized by the alveoli degeneration through apoptosis.
CHI3L1 inhibits mammary epithelial cell differentiation and polarization in the presence of lactogenic hormones, such as prolactin, hydrocortisone and insulin. CHI3L1 suppress CDH1 and increases MMP9 and this is an important process for involution [1](http://www.ncbi.nlm.nih.gov/pubmed/21991364).
In the SOCS3-STAT3 signaling pathway, STAT5 induces SOCS3, which binds to its receptor, IL6ST. Then, IL6ST activates STAT3 [2](http://www.ncbi.nlm.nih.gov/pubmed/16231422). SOCS3/STAT3 signaling pathway is associated with MYC and, thereafter, with MYC target genes such as TP53, BAX and E2F1. Changes in the SOCS3/STAT3 signaling pathway affect MYC. As SOCS3 has an anti-apoptotic function and MYC an apoptotic function, SOCS3 is considered an important regulator of involution [3](http://www.ncbi.nlm.nih.gov/pubmed/17377501).