LPS-induced restriction factors in SM and RM macrophages. MDMs from SMs and RMs were stimulated with LPS, and the fold change in mRNA levels was quantified via real-time PCR relative to unstimulated controls for APOBEC3G, APOBEC3H, TRIM5α, SAMHD1, tetherin, and TRIM22. The relative expression of the LPS receptors CD14, MD2, and TLR4 was assessed in unstimulated MDMs from SMs and RMs. All genes were normalized to the housekeeping gene GAPDH.