Our laboratory has a long-standing interest in B cell antigen receptor (BCR) signaling and BCR dependent processes regulate specific cell fate decisions. In the bone marrow, we have been working to understand how signals initiated through the BCR, in conjunction with those delivered through the IL-7 receptor, coordinate cell cycle progression with immunoglobulin light chain recombination. In the periphery, we have focused on the molecular mechanisms of receptor endocytosis and endocytic trafficking and how these mechanisms influence BCR trafficking and cell fate. As is the case with our studies of lymphopoiesis, we have derived novel in vivo models, and have performed directed in vitro studies, to obtain definitive insights into these processes. In our newest project area, we are applying our knowledge of B cell biology to understanding how in situ adaptive immune responses drive tubulointerstitial inflammation in human lupus nephritis.