Stellar Competent Cells (Use 14 mL round-bottom tubes)
50 uL of cell suspension + 2.5 uL of DNA mix
Incubate on ice for 30 min, heat shock for 45 s at 42 degrees, keep on ice 1-2 min
Add 450 uL SOC medium (warmed up to 37 degrees previously)
Incubate for 1 h at 37 degrees (30 min is also fine if in a rush)
Plate 50 uL on an Amp agar plate
Leave in the incubator at 37C
Alternatively, use any other competent cells and transformation protocol of choice.
Make sure to have a ligation control plate (digested vector with no ligase) to confirm that ligation worked, and to assess the background of any undigested plasmid. In my experience, the ligation works extremely well.
Pick a few clones the following day and grow for mini-preps. Isolate DNA by mini-prep and confirm by Sanger sequencing (You can use universal U6 Fwd primer from Genewiz).
N.B. For the next stage, the expression of GFP does not mean editing took place. Each clone should be tested by an appropriate method (WB, FACS, sequencing) to make sure the location of interest was targeted and the protein of interest was lost.
The same procedure can be applied to clone a gRNA into the Cas9 plasmid with puromycin selection.