ATP6V1C1 and breast cancer: ATP6V1s family members as the components of V-ATPase have been documented to participate in the development of various tumors, such as ATP6V1A implicated in gastric cancer (Wang et al., 2017), ATP6V1C1 implicated in breast cancer (Feng et al., 2013; Cai et al., 2014), esophageal squamous cell carcinoma (Yao et al., 2021), and oral squamous cell carcinoma (Pérez-Sayáns et al., 2010), ATP6V1G1 implicated in glioblastoma (Di Cristofori et al., 2015), and ATP6V1G3 implicated in renal cell carcinoma (Shinmura et al., 2015).