PDCD4 and breast cancer: Taken together, the future research hotspot for the roles of PDCD4 in breast cancer will likely revolve around the following aspects: [1] the function PDCD4 as a biomarker for breast cancer diagnosis, prognosis, and drug-resistance; [2] the identification of novel upstream regulators and downstream target genes of PDCD4 and molecular biological mechanisms; [3] the development of small molecular and targeted drugs related to PDCD4.