(I: Protein expressions of GRP78, CHOP and caspase-12 for NGF-HP treatment in vivo. GAPDH was used as the loading control and for band density normalization. II: The optical density analysis of GRP78, CHOP, and caspase-12 protein in vitro. HP hydrogel, NGF solution and NGF-HP hydrogel were injected in situ (OI). Data are presented as Mean ± SD, n = 5; **P < 0.01 versus a or b group, # P < 0.05 versus d group, determined by two-tailed student’s t-test.)