Inhibition of influenza A/PR/8/34 multiplication in MDCK cells by means of a dominant-negative Cav-1 mutant. Top: Relative titres of MDCK cells expressing myc-tagged dominant-negative caveolin-1 (SD), wild-type (wt) Cav-1 cDNA or mock-transfected cells (Ctrl) 24 h after infection with influenza A/PR8 (m.o.i. = 1) and normalisation to wt MDCK infection (100%). Results of three independent experiments are shown. Bottom: Immunodetection of endogenous, myc-tagged wild-type (wt) and mutant caveolin-1 (SD) in transfected MDCK. Relative protein levels are indicated (endogeneous Cav-1 = 100%). Cav-1 appears in the two known isoforms (Cav-1α 24 kDa; Cav-1β 21 kDa), the β-isoform is missing 31 aminoterminal residues of the Cav-1 protein.