Differential mRNA decay of MAP kinase kinase 6 (MAP2K6), COX2, interleukin-1β (IL1β), and interleukin-8 (IL8) on p38 inhibition detected by Northern blot. The samples used here are identical to one of the three used in the mRNA decay time course experiments in the array hybridizations. See the text for a description of the cell treatments. Times are in minutes. Lane C, no-treatment control. GAPDH, glyceraldehyde-3-phosphate dehydrogenase.