Trabectedin is an originally natural marine product, now obtained by a semisynthetic process, that induces a delay in S phase progression and a blockade in G2 phase of the cell cycle by a mode of action that seems different from that of other DNA-damaging agents (see citations). Although the exact mechanism of action of trabectedin has not been fully elucidated yet, it appears to be unique compared to other anticancer agents (see citations). Trabectedin binds to N2 of guanines in the minor groove of DNA, causing a bending of the minor groove towards the major groove.