Ablation of SK4, however, had a minor effect on mean survival rates but did not significantly prolong tumour‐free survival nor overall survival in the MMTV‐PyMTtg/+ model (Fig. 4), possibly due to an impaired immune and/or stromal cell response, which results in a tumour progression‐promoting microenvironment (Jinushi et al., 2011; Loeffler et al., 2006; Wiseman and Werb, 2002) that counteracts the loss of the oncogenic SK4 functions in the tumour cells. Here, KCNN4 is linked to neoplasm.