Polyphosphate Maintains Intestinal Homeostasis Figure 4. Enzymatically synthesized poly P induced HSP27 from Caco2/BBE cells through the activation of p38 MAPK pathway. (A) HPLC chromatogram of poly P synthesized by PPK. (B) Western blot analysis of HSP27 induction in Caco2/BBE cells by poly P synthesized by PPK (0–100 mg/mL), (n = 3). (C) Poly P degradation by PPK treatment with 10 mM ADP led to an inability to induce HSP27 from Caco2/BBE cells (n = 3). (D) Poly P content in the culture supernatant of L. brevis 8803 at 8, 24 and 24 h from bacterial culture (n = 3). * Significantly different from corresponding control group at P,0.05. doi:10.1371/journal.pone.0023278.g004 PLoS ONE | www.plosone.org 7 August 2011 | Volume 6 | Issue 8 | e23278