To investigate the function of DNAJB9 in breast cancer, the mRNA and protein expression levels of DNAJB9 were measured in luminal cell lines (MCF7, T47D, and BT474) and TNBC cell lines (MDA-MB-231, MDA-MB-157, and Hs578T) using qRT–PCR and western blotting. Here, DNAJB9 is linked to breast carcinoma.