Cytokines secreted by infiltrating immune cells during atherogenesis modulate vascular remodeling. One exemplary event is the antagonism between transformed growth factor (TGF-beta) and interferon gamma (IFN-gamma) on the transcriptional control of type I collagen gene (COL1A2). Previously we have reported that IFN-gamma up-regulates regulatory factor for X-box B (RFXB) to repress collagen transcription while down-regulates the expression of RFXBSV, a splice variant of RFXB that blocks collagen repression in fibroblasts. Here we demonstrate that TGF-beta abrogated COL1A2 repression by IFN-gamma through altering the relative expression of RFXB and RFXBSV. Unlike RFXB, RFXBSV did not bind to the collagen promoter and competed with RFXB for the co-repressor histone deacetylase 2 (HDAC2), limiting HDAC2 recruitment to the collagen transcription start site as evidenced by chromatin immunoprecipitation assays. Over-expression of RFXB by lentiviral infection in HASMCs enhanced HDAC2 enlistment, promoted histone deacetylation surrounding the collagen site by IFN-gamma, and blocked the TGF-beta antagonism, a pattern reversed by RFXBSV infection. On the contrary, silencing of RFXB, but not both RFXB and RFXBSV, expression promoted the TGF-beta antagonism. Thus, we have identified a novel mechanism whereby TGF-beta antagonizes the IFN-gamma repression of collagen transcription in HASMCs and as such provided new insights into antiatherogenic strategies.