Figure S5. Control assays for LPA₁ receptor internalization.

No internalization was found using THC alone. LPA treatment of cells led to high LPA₁ receptor internalization, in accordance with previously published results. LPA₁ receptors were internalized in the presence of THC, providing evidence for a specific THC-mediated effect of the ATX-LPA signaling axis. Inhibition of ATX-LPA signaling by THC is not abolished in the presence of higher LPC concentration (400 µM LPC, P = 0.0068). Untransfected cells were not stained using primary and secondary antibodies, confirming the specificity of the labeling reagents used. Image analysis was performed with ImageJ using nine images per condition from three experimental replicates.