Fig. 2.

Polymixin B (LPS sequester) did not affect sodium laurate (C12:0)- or BSA-complexed palmitic acid (C16:0-BSA)-induced COX-2 expression indicating that the induction of COX-2 expression by these fatty acids is not due to LPS contamination in the fatty acid or BSA preparations. RAW 264.7 cells were serum-starved in 0.25% FBS/DMEM medium for 6 h and then pretreated with 10 ug/ml polymixin B for 1 h followed by coincubation with C12:0, C16:0-BSA, or equivalent concentrations of BSA in the same low-serum medium for 18 h. The protein lysates were probed with anti-COX-2 or anti- β -actin antibody by immunobloting (A, B). Culture medium supernatants were assayed for TNF- α by ELISA (C). Controls: 0.2 ng/ml LPS, 2 ng/ml Pam3CSK4. PM, polymixin B. ** P < 0.01: significantly different from no polymix B control (C).