Proteins of the Rho GTPases family, which include Rac and Cdc42, function as molecular switches. They cycle between an inactive GDP-bound form and an active GTP-bound form, which interacts with downstream effectors to transduce signals. They are activated by guanine nucleotide exchange factors and inactivated by GTPase activating proteins and regulated by Rho GDP-dissociation inhibitors. In humans, a total of 20 Rho GTPases are activated by more than 80 GEFs, which belong to two distinct families, and are inactivated by approximately 70 GAPs and regulated by 3 GDIs. The yeast Saccharomyces cerevisiae has 6 Rho GTPases, yet homologs of Rac, which has been proposed to be the founder of the Rho GTPase family, are not present. Rac1 is, however, ubiquitously present in virtually all other eukaryotes from human to fungi, including in the human opportunistic pathogen Candida albicans. In mammals, Rac1 regulates multiple signaling pathways that control a number of cellular functions, such as cell polarity or gene transcription. The cellular localization of Rac1 is critical for specifying such diverse functions, via site-specific activation/ inactivation and a range of protein interactions. Rac1 cycles between the plasma membrane, where it associates via geranylgeranylation of its carboxy-terminal cysteine residue and the cytosol, where it is bound to RhoGDI. Rac1 has also been shown to accumulate in the nucleus, where it was implicated in different functions, such as cell division, nuclear import of the transcription factor STAT5, accumulation of the armadillo repeat protein smgGDS and for its own proteasome-mediated degradation. One essential feature for Rac1 localization is the presence of a carboxyl-terminal polybasic region, which contains a nuclear localization sequence , preceded by three prolines. Furthermore, both the Rac1 GEF, Dock180, together with the regulatory protein ELMO and the Rac1 GAP, MgcRacGAP have also been observed in the nucleus. Whether the active GTP-bound form or the inactive GDP-bound form of Rac1 accumulates differentially in the nucleus is however controversial. In fungi, Rac1 is also required for different functions such as hyphal differentiation, invasive growth and virulence. In C. albicans, Rac1 and its specific activator Dck1 are dispensable for cell viability and both are required for invasive filamentous growth. Here we investigated the dynamics ofC. albicans Rac1 using FRAP and FLIP approaches, together with the importance of its carboxyl-terminal region for its function and localization. In human cells, Rac1 can localize to the nucleus. In this report, we show that C. albicans Rac1 can also accumulate in the nucleus. Our results indicate that the NLS-consensus Bortezomib motifs in the C. albicans Rac1 carboxyl-terminal region are required for targeting to the nucleus. Geranylgeranylation of the adjacent cysteine residue at position 233 blocks nuclear accumulation as Rac1 was only observed.