Pathway dependency of Src phosphorylation induced by LDK1285, LDK1288, or LDK1305. HEK293 cells expressing CB1 alone, CB1 and β-arrestin 1 siRNA, CB1 and β-arrestin 2 siRNA, CB1 and control siRNA were either untreated (DMSO only) or treated with (A) LDK1285 (10 μM), (B) LDK1288 (10 μM), or (C) LDK1305 (10 μM) for 5 minutes. Cell lysates were separated by SDS-PAGE and analyzed by Western blots probed for phospho-Src (pSrc). The total level of Src was detected for comparison. Quantification of at least three independent experiments is displayed in the right-hand column and expressed as mean S.E.-fold increase above basal level of phosphorylation.