IGFBP7 prolongs IGF1R activation by insulin or IGF1 in primary ALL cells. (A) ELISA results for AKT (Ser473) phosphorylation, (B) INSRβ (Tyr1150/1151) phosphorylation, and (C) IGF1Rβ (Tyr1131) phosphorylation in 11 primary BCP (open circles) and 7 T-ALL (solid circles) cells cultured in AIM-V serum-free medium supplemented with insulin (500 ng/mL), IGFBP7 (100 ng/mL), or a combination of both for 15 minutes and 4 hours. Circles represent means of 2 independent experiments run in duplicate wells. See also supplemental Figures 6, 7, and 8. (D) Dose-response effect for insulin and IGF1, alone or in combination with IGFBP7, on long-term (4 hours) phosphorylation of IGF1Rβ (Tyr1131) as measured by ELISA. Bars represent means ± SE for duplicate wells. (E) Proliferation and (F) survival of REH and Jurkat cell lines stably transduced with IPTG-inducible shRNA vectors against IGF1R or Scramble control (Scr), after 24 and 48 hours of IPTG (1 µg/mL) stimulation, as measured by the trypan blue exclusion technique and Annexin-V/7ADD staining, respectively. Bars represent means ± SE for 2 independent experiments run in triplicate wells. See also supplemental Figure 9A-B. Statistical analysis was done by 1- or 2-way ANOVA and Bonferroni posttests (****P .0001).