Figure 1

Src is expressed and activated in wildtype mammary glands during pregnancy and lactation. The number 4 mammary gland was removed from Src-/- and Src+/+ mice on day 18 of pregnancy (P18) (lanes 1–6), lactation day 2 (L2) (lanes 7–12), and lactation day 9 (L9) (lanes 13–18). Three separate mice were used per genotype and developmental stage. Protein lysates were prepared as described in the Materials and Methods sections, and immunoblotting conducted to detect phosphorylated Src (tyrosine⁴¹⁶) (top panel), total Src (middle panel), total actin, as a loading control (bottom panel).