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Hematopoietic PBX‐interacting protein (HPIP, also known as PBXIP1) is an estrogen receptor (ER) interacting protein that regulates estrogen‐mediated breast cancer cell proliferation and tumorigenesis. However, its functional significance in the context of mammary gland development is unexplored. Here, we report that HPIP is required for prolactin (PRL)‐induced lactogenic differentiation in vitro. Molecular analysis of HPIP expression in mice revealed its induced expression at pregnancy and lactation stages of mammary gland. Moreover, PRL is a lactogenic hormone that controls pregnancy as well as lactation and induces Hpip/Pbxip1 expression in a signal transducer and activator of transcription 5a‐dependent manner. Using mammary epithelial and lactogenic‐competent cell lines, we further show that HPIP plays a regulatory role in PRL‐mediated mammary epithelial cell differentiation, which is measured by acini formation, β‐casein synthesis, and lipid droplet formation. Further mechanistic studies using pharmacological inhibitors revealed that HPIP modulates PRL‐induced β‐casein synthesis via phosphoinositide 3‐kinase (PI3K)/protein kinase B (AKT) activation. This study also identified HPIP as a critical regulator of autocrine PRL signaling as treatment with the PRL receptor antagonist Δ1‐9‐G129R‐hPRL restrained HPIP‐mediated PRL synthesis, AKT activation, and β‐casein synthesis in cultured HC11 cells. Interestingly, we also uncovered that microRNA‐148a (miR‐148a) antagonizes HPIP‐mediated mammary epithelial cell differentiation. Together, our study identified HPIP as a critical regulator of PRL signaling and revealed a novel molecular circuitry involving PRL, HPIP, PI3K/AKT, and miR‐148a that controls mammary epithelial cell differentiation in vitro. [ABSTRACT FROM AUTHOR]

Ethnic identity is a dynamic, multidimensional construct that refers to one's identity, or sense of self as a member of an ethnic group that is identity is constructed and modified as individuals become aware of their ethnicity, within the larger sociocultural sett ing. Achievement of ethnic identity has been found to be an important predictor of self-esteem. It is usually during adolescence that individuals head from an unexamined state of ethnic identity to ethnic identity search as they have interactions that cause them to explore their identities. In a country as diverse as India, the metropolitan societies off er multiple avenues of encounters and interactions with ethnicity, it is a difficult process to achieve and establish ethno-regional identity for emerging adults and middle-aged adults. This correlational study aimed to explore the relationship between ethnic identity and self-esteem in emerging adults and middle-aged individuals living in urban India, and to evaluate diff erences in the two generations. The fi ndings were that emerging adults had greater ethnic identity search than middle-aged adults, and middle-aged adults had greater self-esteem. It was also seen that middle-aged adults who were still in search of ethnic identity had lower self-esteem. This indicates the importance of ethnic identity achievement for self-esteem in adults across generations in urban India. [ABSTRACT FROM AUTHOR]