I am looking for an effective Mouse microglial Cre that can be used to breed with mice expressing global Lox P sites. Using a microglial marker Cre will allow for tissue specific conditional knockdown.
It's not the type of Cre you use that determines its tissue expression pattern, It depends on the promoter you use to drive the expression of the Cre. therefore you must find a microglial cell specific promoter so that you restrict the expression of the Cre to the microglial cells.
and by the way, after finding the suitable promoter, you might want to make the Cre action inducible otherwise it might interfere with your animal's normal development. for example you could use some sort of Tet On system, so that the expression of the Cre can be controlled by Tetracycline, or you could use a Cre-ERT2 fusion so that the Cre can be activated and shuttled into the nucleus, only in the presence of tamoxifen.