It was recently found that in contrast to the bulk of melanoma tumor cells expressing very low levels of JARID1B, a small slow-growing subpopulation expresses high levels of JARID1B. The JARID1B expressing subpopulation was found to act as tumor-initiating cells, giving rise to highly proliferative progeny with low JARID1B expression [47]. This evidence concerns the gene KDM5B and melanoma.