Pursuing her interest, she studied immunology at Flinders University and signed up for a joint program with Commonwealth Scientific and Industrial Research Organization (CSIRO) to study monoclonal antibody technology and potential of monoclonal antibodies as therapeutics.

Then, she had the opportunity to join the research laboratory of Prof Ian Chubb, presently the chief scientist of Australia. It led her towards neuroscience research where she investigated the underlying causes of neural tube birth defects. She found her way into the industry after she met Dr Geoff Grigg, the then head of CSIRO's molecular and cellular biology unit. At that time, he was planning the launch of a company called Peptide Technology (later renamed as Peptech). Dr Rathjen became a co-inventor of Peptech's TNF technology and led the company to successfully defend its key TNF patents against a legal challenge from BASF. This win later provided Peptech with a strong commercial basis for licensing negotiations with BASF, Centocor and other companies with anti-TNF products.
Married with three children, Dr Rathjen gives the credit for her success to her husband. Mr David Rathjen, as she puts it, has been a constant source of encouragement to her. Her stint as a member of the prime minister's Science Engineering and Innovation Council and involvement with issues such as climate change and safe water only further highlight the depth of her role in this industry. She has also been a member of the Australian government's Innovation Australia Board (formerly the Industry Research and Development Board) and a member of the biological committee. Currently, she is a board member of the Australian Nano Fabrication Facility.

A part of this industry for so many years now, Dr Rathjen points out that the risk of execution is still the biggest challenge for the sector. "This requires people with experience, an appropriate use of capital and access to sufficient funding," she explains.

Entrepreneurship, for her, is the key to next level. In her words, "entrepreneurs should be celebrated and entrepreneurship embraced". "At some point, Australia will need to look beyond mining for wealth generation, and the life sciences industry, with its high level of innovation, is one sector that could significantly help the country stay ahead of the curve," she remarks.