While the central role of increased [Ca2+]cyt and STIM1 expression seem well established, further experiments may be needed to elucidate: the mechanisms involved in the first step (initial activation of HIF1 by hypoxia); whether factors additional to increased STIM1 protein are required to activate store-operated Ca2+ entry; and the downstream mechanisms by which increased STIM1 expression and increased [Ca2+]cyt enhance tumor cell growth. The gene discussed is STIM1; the disease is neoplasm.