Cardiac glycoside-induced endosomal recycling could further activate the degradation of other proteins, thus perturbing cancer cell homeostasis Additional extracellular stimuli such as dopamine (Chibalin et al., 1997), parathyroid hormone (Zhang et al., 1999), hypoxia, lung injury (Dada et al., 2003; Lecuona et al., 2009), hypercapnia (Welch et al., 2010), and sepsis (Berger et al., 2011) have been reported to induce internalization of the Na,K-ATPase. Here, PTH is linked to cancer.