Cellular Biology

Throughout the past 2 decades, intense research has linked nu-clear Ca2+ signals to a wide range of physiological and patho-logical cellular responses.1,2 Although nuclear Ca2+ is essential for processes such as nuclear transport, chromatin condensation, and the activation of several transcription factors,3–6 the origin of the nuclear Ca2+ signal is still controversial. Some authors suggest that nuclear Ca2+ signals can result from Ca2+ release that initiates in the cytosol and then propagates to the nucleus,7,8 whereas others suggest that it occurs independently of cytosolic Ca2+ release.9,10 Consistent with the latter notion, we have previously reported that stimulation of the insulin-like growth factor 1 receptor (IGF