Relation between redshift and stellar mass (in solar masses) for the complete zCOSMOS 20 K sample (brown points) and star-forming selected galaxies (violet points). The solid lines show the logarithmic fitting to the limiting masses of the star-forming sample for levels 25%, 50%, and 75% of completeness. Lower and left hand panels also show the distributions for both the complete sample (empty histogram) and the star-forming galaxies (filled histogram) of z and M^∗, respectively.