In human myofibroblasts IGFBP5 silencing decreases survival and promotes apoptosis. (A) Primary human myofibroblasts were transfected with small interfering (si) RNA for IGFBP5 (siBP5) or with a control siRNA (siCtrl). At 16 h after transfection the medium was replaced by serum-free medium. Cells were cultured for an additional 48 h. Then RNA was isolated and IGFBP5 mRNA level determined by quantitative polymerase chain reaction and normalized with 36B4. (B) Recombinant IGFBP5 (rBP5), IGF1 (rIGF1), or both (rIGF1+ rBP5), where added at t = 24 h and 45 h, after replacing the medium, to siBP-5 transfected cells. At 48 h the WST assay was performed. (C) To cells treated as above but grown in 10% fetal calf serum, 0,5 μM gliotoxin was added at 45 h. Caspase 3/7 assay was performed at 48 h. Results are given as a percentage of control cells.