PGR and breast cancer: This inverse relationship between Sprouty4 expression and phosphorylated ERK1/2 signaling was observed both when IDC sample data were pooled (see Fig 1A and 1B) as well as when they were separated into ER/PR+ (n = 67), HER2+ (n = 22), and TNBC (n = 80) breast cancer subtypes (see Fig 1C and 1D).