I am currently using HeLa in my lab.

To activate endogenous STING, we use 2'3'-cGAMP purchased from invivogen.

I have confirmed the 2'3'-cGAMP transfection technique using PEI in several papers, and I also performed transfection at different concentrations and times to utilize it.

(Usually 5-10ug/ml & PEI ratio 1:2 (2'3'-cGAMP 1ug : PEI 2ul))

However, contrary to expectations, phosphorylation of TBK1 was not observed.

(Since the experimental setting for oligomerization of STING using native gel is not possible, I am confirming phosphorylation of TBK1 indirectly.)

If anyone has tried transfection with PEI, please give me some advice.