Figure 4.

POU domain, class 2, transcription factor 3 (POU2F3) is a target of δ-opioid receptor (DOPr)-mediated signaling. Keratinocytes were grown to confluence and differentiation induced by removal of growth factors. POU2F3 expression was analyzed by quantitative real-time PCR. Relative quantity is represented after normalization to RPL13a and the respective vehicle control as reference. (a) POU2F3 expression under influence of methionine⁵ (Met)-enkephalin during 7 days of differentiation. Graphs show mean ±SEM (n=5). Two-way analysis of variance, ***P<0.001. (b) Keratinocytes were differentiated for 24 hours in the presence of 100 nM Met-enkephalin, 100 nM SNC80, 10 μM naltrindole, or vehicle control. Graph represents mean ±SEM (n=4). t-Test, *P<0.05. (c) Keratinocytes were differentiated for 24 hours in the presence of 100 nM Met-enkephalin, 100 nM SNC80, 20 μM of extracellular signal-regulated kinase (ERK) inhibitor PD98059, or vehicle control. The graph represents mean ±SEM (n=4). t-Test, *P<0.05 and ***P<0.001. GFP, green fluorescent protein.