AIMS To compare the proliferative activity of intraepithelial melanocytes in primary acquired melanosis (PAM) without atypia and PAM with atypia by immunohistochemical staining for the Ki-67 antigen and the proliferating cell nuclear antigen (PCNA). METHODS Formalin fixed, paraffin embedded sections from 35 archival specimens of PAM without atypia (n = 19) and with atypia (n = 16) were studie...

Correspondence to Stuart A. Aaronson: [email protected] Abbreviations used in this paper: CM, conditioned medium; dnTCF4, dominantnegative TCF4; ERK, extracellular receptor-dependent kinase; HA, hydroxyapatite; hMSC, human MSC; MSC, mesenchymal stem cell; Osx, osterix; PCNA, proliferating cell nuclear antigen; shRNA, short hairpin RNA; TCF, T cell factor; TCP, tri-Ca phosphate. Introduction

In this issue, a study by Groehler and Lannigan (2010. J. Cell Biol. doi:10.1083/jcb.201002124) sheds light on the regulation of proliferating cell nuclear antigen (PCNA) turnover and how it is counteracted by the small chromatin-bound kinase ERK8 (extracellular signal-regulated kinase 8). Importantly, inactivation of ERK8 results in genome instability and is associated with cell transformation.

DNA replication is a fundamental cellular process that precedes cell division. Proliferating cell nuclear antigen (PCNA) is a central scaffold protein that orchestrates DNA replication by recruiting many factors essential for the replication machinery. We studied the mobility of PCNA in live mammalian cells using single-particle tracking in combination with photoactivated-localization microscop...