Fig 4. Internalization of GPR4 in response to acidification and its inhibition by compound 1.

Permanent cell line expressing GFP-conjugated GPR4 or V_1a vasopressin receptor was incubated for 1 h with or without 1 μM [Arg⁸]-vasopressin (AVP) or 1 μM compound 1 (C1) under the indicated pH to monitor of receptor internalization. After fixation, nucleus was stained with DAPI (blue) and localization of GFP-receptor (green) was monitored. Scale bar: 20 μm. The results are representative of three to four separate experiments. The higher magnification image of the small square is shown in the large square.