Table 1. JAK-STAT and bone development.

Deleted genes	Lethality	Bone phenotype
JAKs
JAK126	Die perinatally	Significantly small body mass.
JAK227,28	JAK2 knockout mice died of anemia at E12.5.	Unknown.
JAK364,65	-	JAK3−/− mice are born normally and develop in an indistinguishable manner from wild-type littermates and show no gross abnormality.
Tyk224,25	-	TYK2-deficient mice are viable and fertile and show no obvious phenotype.
STATs
STAT134-36	-	STAT1−/− mice have higher bone density, but are indistinguishable from their normal counterparts on the basis of size, activity, or ability to reproduce.
STAT243	-	The STAT2 null mice developed and bred normally in specific pathogen-free environment.
STAT338,60,62	STAT3−/− embryos die at E6.5–7.5	Selective inactivation of STAT3 in bone causes osteoporosis.
STAT442,45	-	STAT4−/− mice are grossly indistinguishable from their wild-type littermates.
STAT5A/5B30-32	-	The male and female STAT5A/5B double mutant mice, as well as the male STAT5B mutant mice are significantly smaller than their wild-type littermates. No effect is seen in the STAT5A mutant mice.
STAT641,44,46	-	STAT6−/− mice are grossly indistinguishable from their littermate controls.