Molecular docking (Molegro Virtual Docker, Aarhus, Denmark) has been carried out with Copaifera diterpenoids on cancer molecular targets, including androgen receptor, aromatase, caseine kinase II, cyclin-dependent kinases 2, 4, and 6, cyclooxygenase 2, DNA (cytosine-5)-methyltransferase-1 and -3A, epidermal growth factor receptor, estrogen receptor α, estrogen receptor β, heat shock protein 90, insulin-like growth factor 1 receptor, 5-lipoxygenase, mitogen-activated protein kinase 1, NF-κB, p90 ribosomal protein S6 kinase, P-glycoprotein, phosphatidylinositol-4,5-bisphosphate 3-kinase, topoisomerase I, topoisomerase IIα, topoisomerase IIβ, tubulin, and vascular endothelial growth factor receptor (Table 7). The best overall cancer targets for the copaiba diterpenoids were human DNA (cytosine-5)-methyltransferase-1 (HsDNMT1), human estrogen receptor β (HsERβ), and human mitogen-activated protein kinase 1 (HsMEK1), with average MolDock docking energies of −102.7, −99.2, and −101.5 kJ/mol, respectively. DNA (cytosine-5)-methyltransferase-1 (DNMT1) is the enzyme responsible for DNA methylation of carbon-5 of cytosine within CpG dinucleotides . The enzyme is required for embryonic development , but is overexpressed in lung, liver, colorectal, gastric, breast, and lung tumors . Thus, DNMT1 has emerged as an attractive target for cancer chemotherapy . The mitogen-activated protein kinase (MAPK) signaling cascade is one of the most important pathways involved in cellular proliferation and differentiation  and, therefore, inhibition of components of this pathway, such as MEK1, can potentially target tumors that depend on MAPK signaling . Agonism of estrogen receptor α (ERα) stimulates proliferation of breast, uterus, and prostate tissues, whereas ERβ agonism inhibits proliferation of these tissues . Thus, compounds that can selectively bind and activate ERβ, but not ERα, could represent effective antitumor agents for treatment of prostate and breast cancer . Copalic acid and methyl copalate both targeted HsMEK1, with docking energies of −108.2 and −111.0 kJ/mol, respectively, while 3β-alepterolic acid and 3β-alepterolic acid acetate showed excellent docking with HsDNMT1 (Edock = −107.2 and −121.7 kJ/mol, respectively). Kaurenoic acid was a relatively weakly docking ligand but did show selective docking to aromatase (Edock = −93.7 kJ/mol). The best-docking ligand was patagonic acid, which had a docking energy of −121.8 kJ/mol with HsDNMT1.