The ZFP36 family is a prototypical member of a highly conserved group of proteins with CCCH-type RNA-binding domains, whose functional role and regulatory mechanism in mitotic cells remain obscure. In this study, we provide the first evidence that ZFP36L1 phosphorylation is modulated in a cell cycle dependent manner. The C-terminal region of ZFP36L1 is critical for its cell cycle-dependent phosphorylation of this protein. We also suggest that the phosphorelay-dependent regulation of ZFP36L1 influences mitotic spindle organization. Thus, our data demonstrate a new class of regulatory mechanism for CCCH-type zinc-finger proteins in cell cycle control. (C) 2018 Elsevier Inc. All rights reserved.