Accumulation of HA after bleomycin treatment. (A) HA content was measured by an HA-specific enzyme-linked immunosorbent assay in lungs of wild-type (open square) and CD44-deficient mice (closed square). (B) HA MW at day 7 in lungs of saline-treatedwild-type mouse (top panel, MWaverage 1.443106), bleomycin-treated wild-type mouse (middle panel, MW average 0.54 3 106), and bleomycin-treatedCD44-de?cient mouse (bottom panel, MW averagesfrom left to right 2.10 3 106, 1.41 3 106, 0.16 3 106, and,0.02 3 106). From Teder et al., Science 296, 155 (2002), with permission.