TRPS1 and neoplasm: To probe the oncogenic potential of TRPS1 in vivo, we made use of an orthotopic tumour model for basal breast cancer in which 4T1 cells, a BALB/C-derived tumour cell line, are transplanted into the mammary fat pad of syngeneic immunocompetent BALB/C mice and tumour growth is monitored over time.