PDCD4 and breast cancer: Interestingly, PDCD4 can also inhibit the proliferation and invasion of BC cells by interacting with eukaryotic initiation factor 4A (EIF4A), participating in the down-regulation of mitogen-activated protein kinase kinase kinase kinase 1 (MAP4K1) transcription, and up-regulating p21 to inhibit the transcription of cyclin-dependent kinase 1 (CDK1)/cdc2 [34,35].