A cre sequence was inserted into the BAC clone RP23-224E18, including the murine Calcr promoter and gene in-frame into the third exon shared by the major isoforms. From 11 lines of chimeras obtained, 3 mouse lines were established. One line ID 379 is the most undisturbed nonspecifically by artificial genomic insertion of the transgene, and used for the study. (J:333282)