RPS6KB1 and breast cancer: This is supported by recent reports demonstrating that, in breast cancer cell lines and tumors overexpressing the splicing factor oncoprotein SRSF1, splicing of mRNA encoding S6K1 is modulated and leads to the expression of short S6K1 isoforms devoid of the majority of the kinase domain and the whole C-terminal domain (which contain the acetylation site).