NNMT and breast cancer: Notably, high NNMT expression has been observed in many solid tumors and identified as a marker of malignant degree (Li et al., 2018); these tumors include breast cancer (Wang et al., 2019), renal cell carcinoma (Sartini et al., 2006; Holstein et al., 2019), bladder cancer (Sartini et al., 2013b), non-small cell lung cancer (Sartini et al., 2013a), oral squamous cell carcinoma (OSCC) (Emanuelli et al., 2010; Sartini et al., 2012), skin cancer (Ganzetti et al., 2018; Pompei et al., 2019), esophageal squamous cell carcinoma (Cui et al., 2019), and ovarian cancer (Eckert et al., 2019).