RB1 and breast cancer: Anomalous amplification and mutation of genes cause the initiation of tumors such as a mutation in the Breast Cancer gene (BRCA1/2), RB Transcriptional Corepressor 1 (RB1), Human epidermal growth factor receptor 2 (HER2), Fragile Histidine Triad Diadenosine Triphosphatase (FHIT), tumor protein P53, Epidermal Growth Factor Receptor (EGFR), extracellular signal-regulated kinase (ERK), Mitogen-activated protein kinase (MEK), and Rat sarcoma (Ras) genes that can lead to breast cancer (Figure 1) (Dickson, 1990; Sun et al., 2017; Lakshmithendral et al., 2019a).