A novel cytosolic 58 kd phosphoprotein induced during bone marrow stem cell (BM) differentiation into dendritic cells (DC) during in vitro cultivation with the cytokine GM-CSF by addition of antisera to an 82 kd BM cell surface protein generating cultivatable dendritic progenitor cells (DP). Genes, methods for preparing them as well as early DP have been provided. Potential uses/advantages lie in the study of BM differentiation and innate immunity due to stimulatory/inhibitory DC, contribution of (BM) and DP to inflammation during infection and carcinogenesis, tumor promotion/regression, identification of BM-derived blood cells, T-cell activation/regulation/tolerance and inflammation.