PCLAF and neoplasm: Conflicting studies show that PAF activates or inhibits cell proliferation, suggesting potential roles in tumor promotion or tumor suppression.29 To understand the definitive role of PAF on transformed human mast cells (HMC-1), we cultured HMC-1 cells with 5 μg/ml of carbamyl PAF (cPAF), a non-hydrolysable bioactive PAF agonist, and observed a significant decline in cell proliferation (Figure 1a).