Esophageal cancer-related gene-4 (ECRG4 or C2orf40) has been characterized as a tumor suppressor gene in several types of cancers, such as colorectal cancer (Gotze et al., 2009; Cai et al., 2016), esophageal squamous cell carcinoma (ESCC; Mori et al., 2007; Li et al., 2011; Wen and Hu, 2015), breast cancer (Sabatier et al., 2011; Lu et al., 2013; You et al., 2016; Tang et al., 2019), renal cell carcinoma (Luo et al., 2016), gastric cancer (Deng et al., 2018), and nasopharyngeal carcinoma (Chen J.Y. et al., 2017). Here, ECRG4 is linked to breast carcinoma.