In human monocyte-derived macrophages, the MCPIPgene (monocyte chemoattractant protein-induced protein) is strongly activated by inter-leukin-1b(IL-1b). Using bioinformatics, a PIN domain was identified, span-ning amino acids 130-280; such domains are known to possess structural features of RNases. Recently, RNase properties of MCPIP were confirmed on transcripts coding for interleukins IL-6 and IL-12p40.