B. Effect of USP44 knock down on FOXP3 ubiquitination. Two distinct shRNA lentiviral constructs each containing a G418 resistance cassette were delivered into HEK293T cells. After selected for 7d, cells were transfected with MYC-FOXP3 and His-Ubiquitin, then treated with 20 μM MG132 for 4 hrs before harvest and lysis. Ubiquitinated FOXP3 proteins were visualized as in A. 