Alternative splicing emerges as a potent and pervasive mechanism of gene expression regulation that expands the coding capacity of the genome and forms an intermediate layer of regulation between transcriptional and post-translational networks. Indeed, alternative splicing occupies a pivotal position in developmental programs and in the cell response to external and internal stimuli. Not surprisingly, therefore, its deregulation frequently leads to human disease. In this review we provide an updated overview of the impact of alternative splicing on tumorigenesis. Moreover, we discuss the intricacy of the reciprocal interactions between alternative splicing programs and signal transduction pathways, which appear to be crucially linked to cancer progression in response to the tumor microenvironment. Finally we focus on the recently described interplay between splicing and chromatin organization which is expected to shed new lights into gene expression regulation in normal and cancer cells.