We plot line-widths of the MDCs taken from single-dish and high angular-resolution data. The corresponding sizes are taken from Motte et al. (2007) for the single-dish data, while for the high angular-resolution data sizes show the synthesized beam of the PdBI. The Larson-scaling is indicated by a dotted line. Gray line indicates the fiducial model of McKee & Tan (2003) with a surface density of ~1.7 g cm^-2 and a final stellar mass of 10–60 M_⊙. Different colors indicate the different tracers observed with only single-dish or with the interferometer.