MTTP and Arthritis: As described previously for M-TTP KO (Kratochvill et al, 2011; Qiu et al, 2012) and M-ZFP36L1 KO (Hyatt et al, 2014) mice, the single myeloid-specific KO mice for each of the three genes tested in this study did not exhibit any weight loss, arthritis, premature death or any other external phenotypes in the first several months of age.