TNF-α augments invasion of P. gingivalis through synthesis of mRNAs and proteins. Actinomycin D and cycloheximide inhibited TNF-α-augmented invasion of P. gingivalis in Ca9-22 cells. Confluent Ca9-22 cells were preincubated with 1 μg/ml actinomycin D (Act D) or cycloheximide (CHX) at 37°C for 1 h and were then incubated with TNF-α for 3 h. The cells were further incubated with P. gingivalis (MOI =100) for 1 h. Viable P. gingivalis in the cells was determined as described in Methods. (Means ± standard deviations [SD] [n = 3]). ††, P < 0.01 versus control + TNF-α (-); **, P < 0.01 versus control + TNF-α (+).