EPO and hepatocellular carcinoma: Initially, we discuss how adaptions in erythropoietin‐producing hepatocellular carcinoma (Eph) receptor tyrosine kinase domains resulted in two vertebrate pseudokinases, EphA10 and EphB6, in which co‐evolving sequences generate new motifs that are likely to be important for both nucleotide binding and catalysis‐independent signalling.