Research Paper Volume 16, Issue 3 pp 2789—2811

Figure 2. ER stress and PERK-eIF2α-ATF4 signaling pathway activation are induced by MPPα-PDT in HOS cells. (A) ER morphology was observed by TEM (magnification, ×20000). (B) Intracellular Ca²⁺ concentration was quantified by flow cytometry using Fluo-4-AM probe. (C, D) MPPα-PDT treated cells were harvested after 3, 6, and 12 h and PERK, p-PERK, BIP, p-eIF2α, ATF4, and CHOP, levels determined by western blot. Data are shown as mean ± SD of 3 independent experiments. ^*P < 0.05 vs. control group.