Ptk6 (Brk) expression was shown to enhance the formation of murine ErbB2-induced tumours in cleared fat pads with a shorter latency period than ErbB2-only tumours [12], and both constitutively active and wild-type Brk promoted xenograft growth of MDA-MB-231 basal breast carcinoma cells [16]. Here, ERBB2 is linked to neoplasm.