IPTG (Isopropyl β-D-thiogalactoside) is a non-metabolizable galactose analog that induces expression of the LAC OPERON.

在低浓度时，IPTG通过乳糖渗透酶进入细胞，但在高浓度下（通常用于蛋白质诱导），IPTG可以独立于乳糖渗透酶进入细胞。

For RNA interference (RNAi), A549 cells are plated at 1,500 cells per well in 96-well plates, allowed to adhere for 24 hours, and transfected with 25 nM siRNA oligonucleotide using Dharmafect 4. Transfected cells are treated with the indicated concentrations of GNE-617 (0.1, 1 , 10 , 100 , and 1000 nM) for 72 hours and viability is evaluated with CellTiter-Glo. Lysates for detection of NAPRT1 protein are collected 72 hours after transfection of 1 million A549 cells in 10 cm dishes. For NAPRT1 re-expression, RERF-LC-MS cells are transfected with pCMV6-AC.NAPRT1 and empty vector pCMV6-AC using Amaxa Nucleofector technology and selected with Geneticin