A bacterial lacZ gene was inserted into the gene such that the endogenous gene promoter drives expression of beta-galactosidase. RNA transcripts are detectable in brain, spinal cord, eye, adrenal glands, spleen, lymph nodes, bone marrow, skin, urinary bladder, pituitary gland, salivary gland, tongue, stomach, large intestine, coagulating gland, prostate gland and ovary. LacZ expression was detected: brain, eyes, kidney, urinary bladder, adrenal glands, testis and prostate gland.