The latrunculins are a family of natural products and toxins produced by certain sponges, including genus Latrunculia and Negombata, whence the name is derived. It binds actin monomers near the nucleotide binding cleft with 1:1 stoichiometry and prevents them from polymerizing. Administered in vivo, this effect results in disruption of the actin filaments of the cytoskeleton, and allows visualization of the corresponding changes made to the cellular processes. This property is similar to that of cytochalasin, but has a narrow effective concentration range. Latrunculin has been used to great effect in the discovery of cadherin distribution regulation and has potential medical applications. Latrunculin A, a type of the toxin, was found to be able to make reversible morphological changes to mammalian cells by disrupting the actin network. Latrunculin A: Target and functions Gelsolin - Latrunculin A causes end- blocking; this protein binds to the barbed sides of the actin filaments which accelerates nucleation. This calcium-regulated protein also plays a role in assembly and disassembly of cilia which plays a crucial role in handedness. Latrunculin B: Target and Function Actin- Latrunculin B makes up the structure of the actin fibers. Protein spire homolog 2- needed for cell division, vesicle transport within the actin filament and is essential for the formation of the cleavage formation during cell division[4]. History Latrunculin is a toxin that is produced by sponges. The red-coloured Latrunculia Magnifica Keller is an abundant sponge in the gulf of Eilat and the gulf of Suez in the red sea, where it lives at a depth of 6–30 meters. The toxin was discovered around 1970. Researchers observed that the red-coloured sponges, Latrunculia Magnifica Keller, were never damaged or eaten by fishes, while others were. Furthermore, when researchers squeezed the sponges in the sea, they observed that a red fluid came out. Fishes nearby immediately fled the surrounding area when the sponge secreted the fluid. These were the first indications that these sponges produced a toxin. Later this hypothesis was confirmed by squeezing the sponge in an aquarium with fish, whereupon the fish showed a loss of balance and severe bleeding, dying within only 4–6 minutes. Similar effects were observed when the toxin was injected in mice. Latrunculin makes up to 0.35% of the dry weight of the sponge. There are two main forms of the toxin, A and B. Latrunculin A is only present in sponges which live in the gulf