For example, arginine and glutamate rich 1 (Arglu1) is a transcriptional co-regulator that is essential for estrogen receptor-mediated gene transcription and breast cancer cell growth; it also contains an arginine-serine (RS) domain, which suggests that Arglu1 plays a regulatory role in pre-mRNA splicing [35,36]. This evidence concerns the gene ESR1 and breast carcinoma.