A targeting construct was designed to replace the 3' part of exon 7 and 5' part of exon 8 with a lac-Z-neo cassette by homologous recombination. The vector was intended to create a Lrp5-lacZ fusion protein, however, no Lrp5-containing transcripts were detected by Northern blot, and no Lrp5 or Lrp5-lacZ fusion proteins were detected by Western blot or histochemical staining of liver and bone. (J:104382)