Co-delivery of ATRA and paclitaxel using human serum albumin-bound (ATRA/PTX/HSA) NPs notably reduced MMP-2 and -9 levels in highly metastatic 4T1 mouse breast cancer cells and a murine 4T1 breast tumor model when compared with PTX-NPs or HSA-NPs loaded with single drugs [125]. Here, ALB is linked to breast cancer.