||Summing up all measured protein concentrations listed in the Table (using the maximal values if a range of protein expression is given). This yields ~1.2E8 molecules per cell. In this context, it has been measured that there are ~300 pg total protein per cell. (Volpe and Eremenko-Volpe, 1970)*. Assuming an average protein molecular weight of 60 kDa, one arrives at ~2E9 total protein molecules per cell*. Thus, even the few quantitatively measured signaling proteins listed in the table can (theoretically) make up as much as ~6% of total cellular protein. Similarly, the weights of the measured molecules add up to 14 pg, corresponding to 5% of the cellular protein mass.