STIM1 and breast carcinoma: To determine if exposure to relatively low [D-glucose] resulted in a significant increase in IGFBP-1 transcription in breast cancer cells, MCF-7 and T-47D cells were treated with 1 μM Tam for 24 h in media containing 0, 5.5 or 25 mM D-glucose and total RNA was isolated for quantitative real-time PCR analysis.