def get_fits_from_sample(cells, datatype, ct, tr):
    """
    Returns the fits for the given datatype, celltype and treatment.

    :param cells: dict of cells
    :param datatype: str, datatype
    :param ct: str, celltype
    :param tr: str, treatment
    :return: dict of fits
    """
    sample = cells[ct][tr]
    fits = sample['fits']
    return fits[datatype]