IFNG and infection: This is because, as shown by transcriptional (28, 36) and metabolomics studies [supplemental data file of dynamic changes of metabolites during macrophage polarization in (30)], macrophage polarization to the M1-like phenotype, either induced by pathogen infection or by ligand signaling, such as by LPS and/or IFN-γ, occurs at up to 12 hrs post-treatment or infection.