Tag:CALI(4C) (AEAAAREACCRECCARA) contains a tetracysteine motif that binds the membrane-permeable fluorescein derivative 4',5'-bis(1,3,2-dithioarsolan-2-yl)fluorescein (FlAsH) (PMID:9657724). A protein of interest fused to this tag can be photoinactivated in vivo using the 'fluorophore-assisted light inactivation' (FALI) technique (FBrf0156012).