ANXA1 and infection: By contrast, lentiviral vector-mediated knockdown of annexin A1 showed down-regulation of annexin A1 expression in MHC-positive mdx myotubes (Fig. 4A) and a significantly higher level of cell death (71.1±3.0%) (Fig. 4B) in mdx myotubes after hypo-osmotic shock, compared to the control empty vector infection group (57.7±5.5%).