Down-regulation of MTUS1/ATIP isoforms in SACC. ATIP isoform-specific Real time RT-PCR assays were performed in normal parotid epithelium (PE, n = 3), parotid adenoid cystic carcinoma (PACC, n = 3) tissues and SACC-83 cells. The relative proportions of ATIP1, ATIP3a and ATIP3b transcripts are presented. A: Relative mRNA levels of ATIP isoforms (% of total ATIPs), B: Relative mRNA levels of total ATIPs (% of normal tissue), C: Relative mRNA levels of ATIP isoforms (% of normal tissue). Significant reductions in ATIP1, ATIP3a, ATIP3b and overall ATIP transcripts were observed in the PACC tissue in comparison to normal PE (* P < 0.05). ATIP2 and ATIP4 expression was minimal (less than 1%).