HMGB1 chemotaxis of MEFs requires IKKβ, IKKα, p52, and RelB. Cell migrations with IKKβf/f:CreERT1 (A) or IKKαf/f:CreERT2 MEFs (B) or the same cells pre-exposed to 4-OHT for 36 h (to delete IKKβ or IKKα, respectively) were done in Boyden chambers in SF media or in the same media containing HMGB1 (30 ng/ml) or PDGF (10 ng/ml) (fibroblast migration positive control). Three experiments were done in duplicate. C, Migration responses of WT, p100/p52−/−, and RelB−/− MEFs in SF media, HMGB1 (30 ng/ml), or PDGF (10 ng/ml) for 3 h in Boyden chambers. Two experiments were done in duplicate. In all cases, bars are the mean cell numbers of five high-power fields. All error bars are SEM. *p = 0.02; ***p = 0.002; ****p = 0.0006. HPF, high-power fields.