Take my own field of brain cells, for instance. Of course evolutionists don't regard these as most closely related, but if the molecular patterns were consistent with evolution, they would use it as evidence. This is what I mean by the subjectivity of their criteria. In most vertebrates it is abundant in muscle cells where it serves to replace energy molecules used up during muscle activity. A different but related enzyme is found in nerve cells which have a high ATP turnover.
Vertebrates also have a mitochondrial creatine kinase.
The three different proteins are encoded by three different genes that are found at different locations in the genomes of vertebrates. The data indicates that there were two gene duplications in vertebrate ancestors and this gave rise to three different genes which have evolved independently from that point on. Most of you are probably aware of the evolution of hemoglobin genes which is another example of the same phenomenon. I searched the nucleic acid sequence databases for all creatine kinase sequences and found 74 examples that have been published in the past thirty years. I also searched the protein databases and found 22 more sequences, again there is no record of an elephant or housefly sequence ever being published.