arrest [40–42]. We confirm that PKR activation results in the activation of p38 MAPK in MDA-MB231 cells because PKR inhibitor blocks PIC-mediated p38 MAPK phosphorylation, but a p38 MAPK inhibitor (SB203580) fails to modulate PKR activity. Although SB203580 does not affect PKR, it inhibits PIC-induced phosphorylation of MK2, LIMK1 and cofilin. PIC-induced phosphorylation of MK2, LIMK1 and cofilin is not affected by inhibitors for other MAPKs, such as ERKs and JNKs (data not shown). Taken together, these results indicate the PKR/p38 MAPK/MK2/LIMK1/cofilin pathway is respon- sible for PIC-mediated inhibition of cell motility. It is unclear whether p38 MAPK/MK2 regulates LIMK1 directly or indirectly. MK2 may directly interact and phosphorylate/ activate LIMK1 [24]. However, it is reported that p38 MAPK activates RhoA/ROCK which are upstream of LIMKs by interacting with heat shock protein 27 (HSP27) in MDA-MB435 cells [43]. Kobayashi et al. confirm that p38 MAPK/MK2 References 1. 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