Leukemia/lymphoma-related factor (LRF) is induced during the development of bone-resorbing osteoclasts.  In this manuscript it is found that LRF negatively regulates osteoclast differentiation by repressing nuclear factor of activated T cells c1 (NFATc1) induction in the early phase of osteoclast development, while positively regulating osteoclast-specific genes by functioning as a coactivator of NFATc1 in the bone resorption phase. The stage-specific distinct functions of LRF were demonstrated in two lines of conditional knockout mice in which LRF was deleted in the early or late phase of osteoclast development.

http://www.pnas.org/content/early/2012/01/27/1116042109.long