PTPRD and cancer: Other 2R-ohnologue families displaying high ML skews in 10 or more cancers are those with the following proteins most mutated: potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 1 (HCN1), tectorin alpha (TECTA), receptor-type tyrosine-protein phosphatase delta (PTPRD), low-density lipoprotein receptor-related protein 1B (LRP1B), MAM domain-containing glycosylphosphatidylinositol anchor protein 2 (MDGA2) and protein phosphatase 1 regulatory subunit 9A (neurabin-1) (electronic supplementary material, table S3).