Updated project metadata. Macrophages are sentinels of the immune system and THP1 monocytic cells are one of the widely used models to study immune responses in macrophages. Several monocyte-to-macrophage differentiation protocols exist with phorbol 12-myristate-13-acetate (PMA) being widely used and accepted. However, the concentrations and durations of PMA treatment to induce differentiation varies widely in published literature. In this study, we determined the proteome expression dynamics of THP1 macrophages differentiated from monocytes by three commonly used PMA-based differentiation protocols using dimethyl labeling-based quantitative proteomics analysis. Our analysis shows that variations in PMA concentration and varying periods of rest post-stimulation result in downstream differences in proteome expression and cellular processes. We demonstrate that these differences result in altered expression of cytokines upon stimulation with different TLR ligands. Together, these findings provide a valuable resource that significantly expands the knowledge of protein expression dynamics in in vitro models of macrophages which in turn has profound impact on the immune responses being studied.