When DNAJB4 was knocked down and then overexpressed in MDA-MB-231 and BT-549 breast cancer cells, Western blot analysis showed that the phosphorylation levels of MST1, LATS1, and YAP were restored, while the total protein expression of MST1, LATS1, and YAP1 remained unchanged. This evidence concerns the gene MST1 and breast carcinoma.