CD74 and cyst: We found that knockout of CD74 delayed cyst growth in kidneys from Pkd1flox/flox:Ksp-Cre:CD74−/− mice (n = 9) at postnatal day 7 (PN7) compared to that in age matched Pkd1flox/flox:Ksp-Cre:CD74+/+ mice (n = 7) (Figure 1A).