Alternative splicing represents an economic mechanism to expand and diversify the function of signaling proteins.[26] Meanwhile, emerging data suggest that aberrant splicing promotes tumor growth and thus can be exploited for the development of novel cancer biomarkers.[27] In this study, we identified an alternatively spliced variant of STIM1, STIM1β, that is evolutionarily conserved among mammals but aberrantly upregulated in certain types of cancer, such as glioblastoma. Here, STIM1 is linked to cancer.