NOS2 and neoplasm: Although the mechanism of this anti-neoplastic activity remains to be elucidated, we note that none of the NOS isoforms were detected by RT-PCR in 11 of 12 cultures of enriched tumor cells isolated from the lung tumors induced by AdCre in KrasLSL-G12D/+;Trp53LSL-R172H/+ mice (Supplementary Figure S1C), consistent with previous analysis of NOS expression in human lung cancer patients [10–14].