ATP2C1 and breast cancer: Furthermore, SPCA1 seems to have a direct role in organizing the cargo sorting at the trans-golgi network79, 80 and subsequent departure.81 Functional SPCA1 is important for insulin-like growth factor receptor (IGF1R) processing in basal-like breast cancer, and inhibition of SPCA1 ‘may offer an alternative strategy to direct inhibitors of IGF1R and attenuate the processing of other proprotein convertase substrates...'.82 However, which of the SPCA1 isoforms, if any, works at this level still needs to be defined.