SMAD4 and breast cancer: In contrast, Smad4 was also found to play important oncogenic roles in a vast diversity of cancer types, including breast cancer (Taylor et al., 2013; Xue et al., 2014), ovarian cancer (Chan et al., 2017), glioblastoma (Eichhorn et al., 2012), and HCC (Huang et al., 2018; Moon et al., 2017).