GAPDHS and melanoma: With this threshold, a significant reduction in protein counts occurred when the minimum valid values at protein level were set larger than 50%, resulting in the removal of more than 30% of identified proteins, including some constantly expressed proteins in melanomas/monocytes, such as GAPDHS (Glyceraldehyde-3-phosphate dehydrogenase) in melanoma cells (35) and DUSP3 (Dual specificity protein phosphatase 3) in monocytes (36), respectively (Table 1 and supplemental Table S1).