this letter analyzes two 
 large - scale proteomics studies published 
 in the same issue of nature . at the time of the release 
 , 
 both studies were portrayed as draft maps of the human proteome and 
 great advances in the field . as with the initial publication of the 
 human genome , 
 these papers have broad appeal and will no doubt lead 
 to a great deal of further analysis by the scientific community . 
 however , 
 we were intrigued by the number of protein - coding genes detected by 
 the two studies , numbers that far exceeded what has been reported 
 for the multinational human proteome project effort . 
 we carried out 
 a simple quality test on the data using the olfactory receptor family . 
 a high - quality proteomics experiment that does not specifically analyze 
 nasal tissues should not expect to detect many peptides for olfactory 
 receptors . 
 neither of the studies carried out experiments on nasal 
 tissues , yet we found peptide evidence for more than 100 olfactory 
 receptors in the two studies . 
 these results suggest that the two studies 
 are substantially overestimating the number of protein coding genes 
 they identify . 
 we conclude that the experimental data from these two 
 studies should be used with caution .