CDKN1B and breast cancer: Linichlorin A and Gentian violet were selected out as inhibitors of protein-protein interaction between Skp2-Cks1 and p27Kip1, and they were demonstrated to inhibited p27Kip1 ubiquitination, leading to inhibition of cell growth and delay of cell cycle progression in human cervical cancer cells and murine breast cancer cells (Table 2) (Ooi et al., 2013).