RT-PCR analysis of MARCO in TNF-α–treated (A) HL-60 and (B) U937 cells. (A) Lane 1, MW marker; 2, 3, 4, and 5, HL-60 cells; 2 and 4, without, and 3 and 5, with reverse transcriptase; 2 and 3, without, and 4 and 5, with rhTNF-α. (B) Lane 1, MW marker; 2, 3, 4, and 5, U937 cells; 2 and 4, without, and 3 and 5, with reverse transcriptase; 2 and 3, without, and 4 and 5, with rhTNF-α.