ATXN1 and cervical cancer: Because previous studies have demonstrated variations in cyclin D1 mRNA levels in the cerebellum of both Atxn1−/− and SCA1 knockin mice and cyclin D1 is required for progression from the G1 phase of the cell cycle, we first investigated cyclin D1 expression in SiHa cells, a cervical cancer cell line, using ATXN1 knockdown or overexpression vectors.