SAMHD1 and HIV-1 infection: Since MDMGs were differentiated from peripheral blood monocytes in GM-CSF- and IL-34-containing media, and GM-CSF has been shown to alter the phosphorylation status of SAMHD1 and render MDMs less susceptible to HIV-1 infection (24), we sought to determine the phosphorylation status of SAMHD1 in MDMGs.