Addition of excess proline into the culture medium reversed approximately 57% of HF-mediated inhibition of T cell proliferation (Fig 2), but only 25.7% in the cultures with both RAPA and HF, indicating that the proline depletion is not positively correlated with synergistic interaction of RAPA with HF in the suppression of cell proliferation. This evidence concerns the gene TRERF1 and hydrops fetalis.