FIG. 1.

Targeted disruption of the calpain small subunit gene. Schematic representations show the murine Capn4 allele (upper), the targeting vector (middle), and the targeted allele (lower). The Capn4 gene was cloned from the 129SvJ mouse strain (1). Positions of PstI (P), PvuII (Pv), BamHI (B), and HindIII (H) restriction endonuclease sites are indicated. Homologous recombination replaces a 441-bp PvuII-BamHI fragment containing the 3′ end of Capn4 exon 9 with the neo cassette. Tk, thymidine kinase.