BCAS2, also known as pre-mRNA-splicing factor SPF27, is a ubiquitously expressed nuclear protein that was originally identified as being overexpressed in various breast cancer cell lines. It is now known to be a component of the spliceosome, participating in the removal of introns from mRNA precursors. BCAS2 specifically interacts (in a ligand-independent manner) with TRbeta (thyroid hormone receptor beta), ERalpha (estrogen receptor alpha), ERbeta, PR (progesterone receptor) and PPARgamma (peroxisome proliferator-activated receptor gamma). This protein functions as an ER co-activator and is capable of enhancing ER-mediated transcription. This suggests that BCAS2 is involved in the development of breast cancer.
