As VEGFC and VEGFR3 are biologically fundamental for both angiogenesis and lymphangiogenesis and severe complications occur either by loss of function (e.g., lymphoedema) as a gain of function (e.g., metastases), it is vital to discover tools that adjust VEGFC and VEGFR3 activity and signalling (Bahram & Claesson‐Welsh 2010). Here, FLT4 is linked to lymphedema.