Fig. 2: BH4 metabolism protects pulmonary cells from radiation-induced damage.

a HELF cells were infected with the control adenovirus or GCH1 adenovirus and subsequently irradiated. Cell viability was measured by a CCK-8 assay at 24, 48, and 72 h after irradiation. The effect of GCH1 overexpression on the survival of (b) HELF and (c) BEAS-2B cells was evaluated. HELF and BEAS-2B cells were treated with BH4 or PBS and subsequently irradiated. d, e The clonogenic survival of the two cell lines was measured. f, g HELF and BEAS-2B cells were subjected to LDH release assays. *P < 0.05 and **P < 0.01 compared with the control group.