Further, hsa-miR-224 promotes tumorigenesis through down-regulation of caspase-9 in triple-negative BC (Zhang et al., 2019), hsa-miR-574 enhances doxorubicin resistance by down-regulating SMAD4 in BC cells (Sun et al., 2018), and hsa-miR-130a suppresses BC cell migration and invasion (Chen et al., 2018; Kong et al., 2018) and reduces drug resistance in BC (Huang et al., 2019). The gene discussed is SMAD4; the disease is breast cancer.