We selected two upregulated and two downregulated ABC genes with significant prognostic values for various subtypes of breast cancer and further demonstrated that the upregulated ABC genes, DYNLT3 and P4HA3, have a tumor-promoting function whereas the downregulated gene ALX4, but not WDR86, showed tumor-suppressive function by in vitro and in vivo experiments. Here, P4HA3 is linked to breast cancer.