ERBB2 and mastocytosis: Various pyrimidine-containing derivatives are used in a variety of cancer treatments, e.g., Dinaciclib is used as CDK, Cytarabine as induction chemotherapy, Avapritinib in the treatment of mastocytosis, Neratinib and Afatinib as a tyrosine kinase inhibitor, osimertinib, Gefitinib as EGFR TKI, Lapatinib as HER2/neu EGFR, Ibrutinib as Bruton’s tyrosine kinase, Sapanisertib as an inhibitor of mTOR, Umbralisib as PI3K-delta and casein kinase CK1-epsilon (Figure 9).