4.4.1.20	phosphoprotein	phosphoregulation of LTC4S, as increased activity during MM6 cell differentiation correlates with reduced phosphorylation of 70-kDa ribosomal protein S6 kinase, which can phosphorylate purified LTC4S. The ribosomal protein S6 kinase inhibitor rapamycin at 20 nM doubles LTC4S activity of undifferentiated MM6 cells, and protein kinase A and C inhibitors H-89, CGP-53353, and staurosporine reverse the zymosan-induced suppression of LTC4S activity	714941	
4.4.1.20	phosphoprotein	residue Ser36 is the major p70S6k phosphorylation site, along with a low frequency site at Thr40	748212